Wing fold controller

ABSTRACT

Illustrative embodiments may provide for an apparatus and method of controlling the folding of a wing. The apparatus may include a sensor, an actuator, and a wing fold controller. The method may include receiving a status of at least one of an aircraft and a wing fold system of the aircraft by the wing fold controller of the wing fold system. The method may also include receiving an automated command by the wing fold controller in response to receiving the status. The method may also include operating the wing fold system by the wing fold controller based on the automated command and the status. The method may also include transitioning a wingtip of a wing of the aircraft to one of a flight position and an on-ground position by an actuator of the wing fold system in response to commands from the wing fold controller.

CROSS REFERENCE AND PRIORITY

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/022,622, filed Sep. 10, 2013, which claims the benefit ofProvisional U.S. Patent Application No. 61/720,338, filed Oct. 30, 2012;and is also a continuation-in-part of U.S. patent application Ser. No.13/664,416, filed Oct. 30, 2012, which is a continuation-in-part of U.S.patent application Ser. No. 13/251,216 filed Oct. 1, 2011; the entiredisclosures of each of the above noted applications are incorporated byreference herein.

FIELD OF THE DISCLOSURE

This disclosure relates to systems and methods for controlling wings,and more specifically, to systems and methods for controlling wingtipsto enhance aircraft performance and fuel efficiency.

BACKGROUND OF THE DISCLOSURE

In the commercial air transport industry, it is desirable to designaircraft configurations that yield reduced fuel burn per seat-mile, asfuel burn per seat-mile is a measure of fuel efficiency. Efficientaircraft configurations are ever more important as fuel costs continueto increase. Aircraft aerodynamic drag and fuel burn are generallyreduced as the aspect ratio of the aircraft wing increases. Similarly,operating larger aircraft which carry more passengers and payload isgenerally more efficient between two destinations than flying severaltrips with smaller aircraft. Thus, larger aircraft and aircraft withlonger wingspans tend to be more efficient. However, taxiway spacing andgate locations for most airports were established without providingadequate spacing for aircraft with the longer wingspans that may beproduced with today's technology.

Some attempts have been made to improve aircraft wing efficiency withoutadding wingspan. Winglets extending vertically from the wingtips haveimproved aircraft fuel efficiency without significantly increasingwingspan. However, the efficiency added by winglets may not be asbeneficial as that provided by extending the wingspan.

Therefore, it would be desirable to have a method and apparatus thattakes into account at least some of the issues discussed above, as wellas other possible issues.

SUMMARY

The illustrative embodiments may provide a method of controlling foldinga wing. The method may include: receiving a status of at least one of anaircraft, and controlling, via a wing fold system of the aircraft,folding the wing. The method also may include receiving an automatedcommand by the wing fold controller of the aircraft in response toreceiving the status. The method also may include operating the wingfold system of the aircraft by the wing fold controller based on theautomated command and the status. The method also may includetransitioning a wingtip of a wing of the aircraft to one of a flightposition of the wing and a folded position of the wing by an actuator ofthe wing fold system in response to operating the wing fold system bythe wing fold controller.

The illustrative embodiments may also provide for an apparatus tocontrol a wing fold system of a wing of an aircraft. The apparatus mayinclude a wing fold controller configured to receive a status of atleast one of the aircraft or the wing fold system of the aircraft. Theapparatus also may include the wing fold controller configured toreceive an automated command based on receiving the status. Theapparatus also may include the wing fold controller configured tooperate the wing fold system of the aircraft based on the command andthe status. The apparatus also may include an actuator configured totransition a wingtip of a wing of the aircraft to one of a flightposition of the wing and a folded position of the wing in response tooperating the wing fold system by the wing fold controller.

The illustrative embodiments may also provide for an aircraft. Theaircraft may include a fuselage configured for flight and a computer.The computer may include a bus, a processor connected to the bus, and amemory connected to the bus, the memory storing a program code which,when executed by the processor, performs a computer-implemented method.The program code may include program code for receiving a status of atleast one of an aircraft and a wing fold system of the aircraft by thewing fold controller of the aircraft. The program code also may includeprogram code for receiving an automated command by the wing foldcontroller of the aircraft in response to receiving the status. Theprogram code also may include program code for performing, using theprocessor, operating the wing fold system of the aircraft by the wingfold controller based on the command and the status. The program codealso may include program code for performing, using the processor,transitioning a wingtip of a wing of the aircraft to one of a flightposition of the wing and a folded position of the wing by an actuator ofthe wing fold system in response to operating the wing fold system bythe wing fold controller.

The features, functions, and benefits may be achieved independently invarious embodiments of the present disclosure or may be combined in yetother embodiments in which further details can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the illustrativeembodiments are set forth in the appended claims. The illustrativeembodiments, however, as well as a preferred mode of use, furtherobjectives and features thereof, will best be understood by reference tothe following detailed description of an illustrative embodiment of thepresent disclosure when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a diagram of an aircraft embodying a wing fold controller inaccordance with an illustrative embodiment;

FIG. 2 is a diagram of an aircraft embodying a wing fold controller inaccordance with an illustrative embodiment;

FIGS. 3A and 3B are a flowchart of a method of folding a wing via a wingfold controller in accordance with an illustrative embodiment;

FIG. 4 is a block diagram of an aircraft embodying a wing foldcontroller in accordance with an illustrative embodiment;

FIG. 5 is a block diagram of a wing fold system in accordance with anillustrative embodiment;

FIG. 6 is a diagram of a wing embodying a wing fold system in accordancewith an illustrative embodiment;

FIGS. 7A and 7B are a flowchart of a method of a wing fold controller inaccordance with an illustrative embodiment;

FIG. 8 is a flowchart of a method of manufacturing a commercialaircraft;

FIG. 9 is a block diagram of a commercial aircraft; and

FIG. 10 is an illustration of a data processing system, in accordancewith an illustrative embodiment;

FIG. 11 is a plan view diagram of a wing fold system, in accordance withan illustrative embodiment;

FIG. 12A, FIG. 12B, FIG. 12C, and FIG. 12D represent a cross-sectionalplan view diagram of a lock for a latch of a wing fold system, inaccordance with an illustrative embodiment; FIG. 12A is across-sectional plan view diagram of a latch in a closed position with alock in a disengaged position and respective centerlines of fixed lugs,unfixed lug, and a lock, substantially aligned in accordance with anillustrative embodiment; FIG. 12B is a cross-sectional plan view diagramof a lock unable to engage with misaligned lugs of a latch in accordancewith an illustrative embodiment; FIG. 12C is a cross-sectional plan viewdiagram of a lock in a disengaged position when a centerline axis of anunfixed lug may not align with a centerline axis of fixed lugs and acenterline axis of a lock in accordance with an illustrative embodiment;FIG. 12D is a plan view diagram of a lock in an engaged position in aclosed latch in accordance with an illustrative embodiment.

FIG. 13 is a chart indicating moments about a wing fold actuator hinge,in accordance with an illustrative embodiment;

FIG. 14A, and FIG. 14B represent diagrams of components for a hydrauliccontrol system for a wing fold system that includes FIG. 14A and FIG.14B, in accordance with an illustrative embodiment; FIG. 14A is adiagram for a hydraulic control system for a wing fold system with amotor driven by variable differential hydraulic power, in accordancewith an illustrative embodiment; FIG. 14B is a diagram for a hydrauliccontrol system for a wing fold system with a motor driven by fixeddifferential hydraulic power, in accordance with an illustrativeembodiment.

FIG. 15 is a flowchart of a method for controlling an angular free playof an unfixed portion of a wing relative to a fixed portion of the wingwhile transitioning a lock in a latch, in accordance with anillustrative embodiment; and

FIG. 16 is a flowchart of a method for decreasing a load on a wing foldactuator of a wing, and increasing a mean time between replacement ofthe wing fold actuator, relative to the wing foregoing using theprocess, in accordance with an illustrative embodiment.

DETAILED DESCRIPTION

Illustrative embodiments may recognize and take into account one or moredifferent considerations. For example, having an aircraft that maybenefit from a long wingspan in flight, while being able to reduce thewingspan when operating at an airport such as but not limited toInternational Civil Aviation Organization “code E” or Federal AviationAdministration “code V” airports, may be desirable with respect toincreasing the flexibility of where an aircraft may operate. Inparticular, by being able to reduce the wingspan while on the ground, anaircraft may be able to operate at more airports than if the aircraftcould not reduce its wingspan while on the ground. With the longerwingspan during flight, benefits may include fuel efficiency.

Thus, control of the wingspan of an aircraft may be advantageouslyachieved through the use of a wing fold controller and wing fold system.The wing fold controller receives status of the aircraft and wing foldsystem and also receives commands to control the state of the wing foldsystem. Based on the status and the commands, the wing fold controllertransitions the wing fold system between a folded position and a flightposition, therein controlling the wingspan of the aircraft.

The illustrative embodiments may allow for folding and extending ofwingtips that may be based on, without limitation, information aboutaircraft status and/or the environment around the aircraft. Folding andextending of wingtips may be automated.

Aircraft status may include, without limitation, a configuration of theaircraft, or a condition of any aircraft status that may affect anycomponent or feature of a wing fold system. The environment around theaircraft may include, without limitation, aircraft location duringpreparation for takeoff or after landing, and/or structures, obstacles,or vehicles and/or weather phenomenon around the aircraft.

Architecture provided herein includes an electronic wingtip foldingsystem that may allow for higher availability based in part on additionof redundant system components. Such components may include controllers,analog to digital converters, control lanes, control channels, and/orsensors. The system may be more adaptive to automated operation than anyexisting wing fold system.

The illustrative embodiments may promote more ease in modification towingtip folding functionality. Such functionality may includemodification of software code as opposed to altering mechanical hardwareand kinematic interfaces. Diagnostic capability of the wingtip systemmay include earlier detection of vulnerable components which may reducetime of exposure to latent vulnerabilities.

The system may be less subject to dynamic mechanical feedback. Theillustrative embodiments may promote greater ease in verifyingfunctionality of the system, allowing for checks of the system forpossible latent problems via automated, periodic system tests. Forexample, the system may verify that a moveable wingtip may be latched orlocked to a fixed wingtip. The system may automatically attempt to foldthe wingtip after sensing the wingtip may be in a latched and lockedconfiguration. If the attempt is not successful in moving the wingtipsystem, the aircraft may be verified to be in a flightworthy condition(with regard to the wingtips). If the system is able to move the wingtipor critical parts of the system, then a crew-alerting system mayannunciate that the aircraft is in a non-flightworthy condition.

The illustrative embodiments may promote a reduced workload on crew.Minimal or no crew actions may be required to configure wingtips forflight or ground operations including taxiway and gate operations.Location-based alerting may also be promoted. Prior to takeoff, thesystem may verify that the aircraft may be in flightworthy configurationbefore engine thrust may be applied. After landing touchdown, the systemmay verify that the aircraft may be in a correct configuration foroperation around the airport where reduced wingspan is required such as,without limitation, taxiway, other runway, gate, ramp, apron, and/ormaintenance facility operations.

The illustrative embodiments may provide improvements over previous wingcontrol arrangements that may require large spatial integration volume.Such previous requirements may result in increased wing loft that maycause excess drag and greater weight. Previous arrangements also may notbe readily modified or optimized once their designs are finalized.

By contrast, the illustrative embodiments may provide a more electricaland optical control which may reduce component volume and allow foroptimization and modification via software updates. Further, theillustrative embodiments may alleviate concerns over lightning strikesand electromagnetic effects when considering optical signaltransmission. A more electric architecture may allow for easier buildand maintainability of aircraft through installation of replaceablecomponents as opposed to mechanical components that may requireindividual shimming and rigging.

Unless otherwise noted and where appropriate, similarly named featuresand elements of an embodiment of one figure of the disclosure correspondto and embody similarly named features and elements of embodiments ofthe other figures of the disclosure.

Attention is turned to the figures. FIG. 1 is a diagram of an aircraftembodying a wing fold controller in accordance with an illustrativeembodiment. FIG. 2 is a diagram of an aircraft embodying a wing foldcontroller in accordance with an illustrative embodiment. Referencenumerals used in FIG. 1 are also used in FIG. 2.

Aircraft 100 may be an example of an aircraft in which a wing foldsystem may be implemented in accordance with an illustrative embodiment.In an illustrative embodiment, aircraft 100 may include wing 102 andwing 104 attached to body 106; engine 108 attached to wing 102; engine110 attached to wing 104. FIG. 1 depicts wings 102 and 104 of aircraft100 in a flight position, with wingspan 132. FIG. 2 depicts wings 102and 104 aircraft 100 in a folded position, with wingspan 202. Wingspan202 may be less than wingspan 132.

Wing 102 may include fixed portion 124 and unfixed portion 120. Fixedportion 124 may be an inboard portion of wing 102, which may be fixed tobody 106. Similarly, wing 104 may include fixed portion 126 and unfixedportion 122. Wing 102 may include wing fold system 130 to move unfixedportion 120 with respect to fixed portion 124. Wing 104 may include wingfold system 128 to move unfixed portion 122 with respect to fixedportion 126.

Body 106 has tail section 112. Horizontal stabilizer 114, horizontalstabilizer 116, and vertical stabilizer 118 are attached to tail section112 of body 106. Wing fold system 128 and wing fold system 130 eachinclude a latch assembly (not depicted in FIG. 1 or FIG. 2) inaccordance with an illustrative embodiment.

FIGS. 3A and 3B are a flowchart of a method 300 of folding a wing via awing fold controller in accordance with an illustrative embodiment.Method 300 shown in FIG. 3 may be implemented using aircraft 100 of FIG.1 and FIG. 2. The method shown in FIG. 3 may be implemented by aprocessor, such as processor unit 1004 of FIG. 10. The method shown inFIG. 3 may be a variation of the processes shown in FIG. 1 and FIG. 2and FIG. 4 through FIG. 10. Although the operations presented in FIG. 3are described as being performed by a “method,” the operations are beingperformed by at least one tangible processor or using one or morephysical devices, as described elsewhere herein. The term “method” alsomay include computer instructions stored on a non-transitory computerreadable storage medium.

Method 300 may begin as the method may receive a status of at least oneof an aircraft and a wing fold system of the aircraft by the wing foldcontroller of the aircraft (operation 302). The status may be displayedon a display.

Next, the method may receive a command by the wing fold controller ofthe aircraft in response to receiving the status (operation 304). Thecommand may be an automated command.

Next, the method may operate the wing fold system of the aircraft by thewing fold controller based on the command and the status (operation306). Next, the method may transition a wingtip of a wing of theaircraft to one of a flight position of the wing and a folded positionof the wing by an actuator of the wing fold system in response tooperating the wing fold system by the wing fold controller (operation308).

Next, the method may indicate, via the status, that the aircraft may beon a taxiway and the command directs the wing to the folded position(operation 310). Alternatively, the method may indicate, via the status,that the aircraft may be rolling toward a taxiway and the commanddirects the wing to the folded position.

Next, the method may indicate, via the status, that the aircraft may beon a runway and the command directs the wing to the flight position(operation 312). Alternatively, the method may indicate, via the status,that the aircraft may be rolling toward a runway and the command directsthe wing to the flight position. Next, the method may display the statusof the wing fold system on a display (operation 314).

Next, the method may determine, via the wing fold controller, if a lockof the wing fold system may be operational via attempting to move thewingtip via the actuator after the lock of the wing fold system may bein an engaged position (operation 316). Operation 316 may also be a testof the operation of a latch of the wing fold system.

Next, the method may communicate a warning in response to attempting tomove the wingtip after the lock may be in the engaged position(operation 318). Next, the method may determine, via the wing foldcontroller, that the status prevents the command (operation 320).

Next, the method may prevent, via the wing fold controller, the wingtipactuator from transitioning the wingtip when the status prevents thecommand (operation 322). Next, the method may transition, via a latchactuator, a latch of the wing fold system of the aircraft to one of anopen position and a closed position after the wingtip transitions to theflight position (operation 324). Next, the method may transition, via alock actuator, a lock of the latch of the wing fold system of theaircraft to one of: an engaged position, and a disengaged position thatprevents movement of: the latch, and the wingtip (operation 326).

Next, the method may communicate a warning in response to receiving thestatus, when the status indicates that a location of the aircraftrequires a different position of the wingtip (operation 328). Next, themethod may indicate, via the status, that the wingtip may be in theflight position, and that the location of the aircraft may be one of: ona taxiway, and at a gate (operation 330). Alternatively, the aircraftlocation may be inside a building or in proximity to a vehicle orobstacle that the wing fold controller may predict may contact thewingtip. Further, the aircraft may be rolling toward a taxiway, a gate,a building, a vehicle or obstacle that the wing fold controller maypredict may contact the wingtip.

Next, the method may indicate, via the status, that the wingtip may bein the folded position, and the location of the aircraft may be on arunway (operation 332). Alternatively, the aircraft location may berolling toward a runway.

FIG. 4 is a block diagram of an aircraft embodying a wing foldcontroller in accordance with an illustrative embodiment. Aircraft 400may be an illustrative embodiment of aircraft 100 depicted in FIG. 1 andFIG. 2. Aircraft 400 may include several features, elements, andcomponents, including: status 402, control center 416, wing foldcontroller 428, and wing 442.

Status 402 may include aircraft information 404 and location information410. Aircraft information 404 may include information related toaircraft 400 that may be used by wing fold controller 428 to controlwing fold system 458. Aircraft information 404 may indicate a statusincluding, without limitation, one or more of: whether aircraft 400 maybe in-flight, whether aircraft 400 may be standing, whether aircraft 400may be taxiing, whether aircraft 400 may be performing a takeoff,whether aircraft 400 may be performing an initial climb, whetheraircraft 400 may be en route, whether aircraft 400 may be maneuvering,whether aircraft 400 may be performing an approach, whether aircraft 400may be landing, a speed of aircraft 400, a wind speed of air surroundingaircraft 400, a status of an aircraft system, and/or whether aircraft400 may be in a flightworthy configuration. An aircraft that may bestanding may be aircraft 400 that may be on the ground, but the locationinformation 410 of aircraft 400 may not be changing. An aircraft systemthat may be used by wing fold controller may include, withoutlimitation, a hydraulic system, an electrical system, wiring, anactuator, and a controller.

Location information 410 may include information related to a positionof aircraft 400 relative to its surroundings that may be used by wingfold controller 428 to control wing fold system 458. Surroundingsrelated to aircraft 400 may include, without limitation: a taxiway, anapron, a de-icing station, a run-up pad, a runway, a gate, a maintenancefacility, any obstacle, and/or any vehicle. Information on relativesurroundings may be provided by, without limitation, an onboarddatabase, datalinked information, Global Positioning System (GPS)derived information, radar, and/or Automatic DependentSurveillance-Broadcast (ADS-B) derived information. Location information410 may indicate and may be used to determine if wing 442 may berequired to be in folded position 446, such as when aircraft 400 may beat a point on an airport, such as on a taxiway or at a gate, that mayrequire a limited wingspan.

Control center 416 may be a cockpit in aircraft 100. Alternatively,control center 416 may be outside aircraft 100 and connected via datalink to aircraft 100. Without limitation, control center 416 may includea maintenance facility or computer system. Control center 416 maycontain input device 420, display 418, and warning system 426. Inputdevice 420 may be used to control and operate aircraft 100. Withoutlimitation, input device 420 may be include a switch, screen or devicein a cockpit, a controller or other processor in or linked to aircraft400, or by an aircraft operator in control center 416. An aircraftoperator may be a crew member in a cockpit, or another operator, whichmay be a processor in control center 416.

Display 418 may display any portion of status 402 to aircraft 400.Display 418 may be viewed by an operator of aircraft 400. Display 418may be one of several displays in control center 416 that are of anytype, size, or shape to display information to crew members. Display 418may be a touch sensitive display to allow for inputs from a crew memberto control aircraft 400 via display 418.

Input device 420 may control operation of aircraft 400 and allowcommand(s) 430 to be sent to wing fold controller 428. Input device 420may include any number of flight controls 422 that control flight ofaircraft 400. Flight controls 422 may include thrust lever 424 thatcontrols thrust of aircraft 400. Input device 420 may include display418 when display 418 allows for inputs.

Warning system 426 of aircraft 400 may issue warnings 460 to controlcenter 416 or to associated facilities. Without limitation, associatedfacilities may include: air traffic control facilities, airline dispatchfacilities, or airline or manufacturer maintenance facilities. Warnings460 may include transmissions to an airport control tower, to nearbyaircraft, to a dispatcher for aircraft 400, to a maintenance monitor foraircraft 400, and/or to other systems outside aircraft 400 that monitoraircraft 400. Warnings 460 may indicate when wingtip 456 of wing 442 maybe not in a proper position based on status 402 of aircraft 400.Warnings 460 may also indicate when wing fold system 458 may be notproperly functioning. Warnings 460 may be communicated visually,mechanically, electronically, and/or audibly. Warnings 460 may bedisplayed via display 418. Warnings 460 may be integrated into existingtakeoff or landing configuration warning systems. Warnings 460 may be asingle warning or a plurality of warnings. The single warning or theplurality of warnings may be sent to a single recipient or to multiplerecipients.

When thrust lever 424 of aircraft 400 may be moved to a position thatmay be inappropriate for a position of wingtip 456, command 430 ofthrust lever 424 may be prevented. If thrust lever 424 may be moved to atakeoff position, but wingtip 456 may be in a position that may not beallowed for takeoff, such as folded position 446, warnings 460 may beissued. Further, command(s) 430 to increase thrust may be preventeduntil wingtip 456 may be in an appropriate position. Alternatively, oradditionally, wing fold controller 428 may command 430 wingtip 456 toflight position 444. Command 430 may be an automated command.

Warning system 426 may send warnings 460 based on a location of aircraft400. Warnings 460 may include aircraft location data. Warnings 460 mayinclude a recommended action to mitigate warnings 460. Location-basedwarnings 460 may be used before takeoff to verify aircraft 400 may be ina correct configuration for takeoff when aircraft 400 approaches thetakeoff end of a runway. The correct configuration may be based onaircraft information 404. Aircraft information 404 may include aposition of wingtip 456. Thus, warning system 426 may issue warnings 460if wingtip 456 was not extended in flight position 444 before takeoff.

Warnings 460 based on location information 410 of aircraft 400 may beused after landing to verify aircraft 400 may be in a correctconfiguration for airport compatibility. The correct configuration forairport compatibility may include having wingtip 456 in folded position446 before aircraft 400 operates on designated airport areas. Designatedairport areas may include a taxiway, an apron, a de-icing station, arun-up pad, a runway, a gate, and/or even certain runways. For example,an airport may limit taxiway use to certain aircraft wing-span lengths.If aircraft 400 wingspan exceeds a particular taxiway wingspan limitwith wingtip 456 in flight position 444, but aircraft 400 may be withinthe limit when wingtip 456 may be in folded position 446, warnings 460could be issued before aircraft 400 enters the particular taxiway withwingtip 456 in flight position 444. As another example, warning system426 may issue a warning if aircraft 400 was approaching a gate with awingtip configuration exceeding a wingspan limit of the gate.

Wing fold controller 428 may include any grouping of one more processorsand programs of aircraft 400 that operate aircraft 400. Wing foldcontroller 428 may be a component of a computer inside control center416, a component of a computer outside control center 416, a componentof a computer or controller of wing fold system 458 in wing 442, or anycombination thereof.

Wing fold controller 428 may receive status 402 related to aircraft 400and to wing fold system 458. Wing fold controller 428 may receivecommands 430 via at least crew input commands 434. Wing fold controller428 may operate wing fold system 458 based on command(s) 430 received.

Wing fold controller 428 may determine that a lock of wing fold system458 may be operational. If the lock may be operational, then wingtip 456should not be able to move when wingtip 456 may be in flight positionand the lock may be engaged. To make the determination, wing foldcontroller 428 may attempt to move wingtip 456 after a lock of wing foldsystem 458 may be in an engaged position with respect to a latch of wingfold system 458 that may be in a closed position. Wing fold controller428 may attempt to move wingtip 456 by attempting to move unfixedportion 454. Wing fold controller 428 communicates warnings 460 viawarning system 426 in response to attempting to move wingtip 456 whenwingtip 456 moves even though the lock may be in the engaged positionand the latch may be in the closed position.

Wing fold controller 428 may be a single microcontroller ormicroprocessor, or may be one in a group of processors of aircraft 400.Wing fold controller 428 may receive input data, status data, andconfiguration data. Wing fold controller 428 may send command data andalert data based on input data, status data, and configuration data.

Wing fold controller 428 may be implemented in software, hardware, or acombination of software and hardware. When software may be used, theoperations performed by wing fold controller 428 may be implemented inprogram code configured to run on a processor unit. The processor unitmay, for example, be one or more central processor units in a computersystem that may be a general purpose computer. General purpose computersare described with respect to FIG. 10.

When hardware may be employed, the hardware may include circuits thatoperate to perform the operations in wing fold controller 428. In theillustrative examples, the hardware may take the form of a circuitsystem, an integrated circuit, an application specific integratedcircuit (ASIC), a programmable logic device, some other suitable type ofhardware configured to perform a number of operations, or a combinationthereof. With a programmable logic device, the device may be configuredto perform the number of operations. The programmable logic device maybe reconfigured at a later time or may be permanently configured toperform the number of operations.

Examples of programmable logic devices may include, for example, aprogrammable logic array, programmable array logic, a field programmablelogic array, a field programmable gate array, and other suitablehardware devices. Additionally, the processes may be implemented inorganic components integrated with inorganic components and/or may beincluded entirely of organic components excluding a human being. Forexample, the processes may be implemented as circuits in organicsemiconductors.

Command(s) 430 may be received by wing fold controller 428. Command(s)430 may be received from input device 420. Types 432 of command(s) 430include crew input commands 434, automated commands 436, maintenancecommands 438, and factory commands 440. Command(s) 430 may be any one ofor a combination of crew input commands 434, automated commands 436,maintenance commands 438, and factory commands 440. Command(s) 430 maybe used to control wing fold system 458.

Wing 442 may be an illustrative embodiment of wing 102 and/or wing 104in FIG. 1 and FIG. 2. Wing 442 may include flight position 444, foldedposition 446, fixed portion 448, unfixed portion 454, and wing foldsystem 458. The folding of wing 442 may allow for aircraft 400 to beflown with a wingspan that may be longer than that allowed for groundoperations at an airport from which aircraft 400 may take off and land.Wing 442 may provide lift for aircraft 100 in FIG. 1.

Flight position 444 may be a state of wing 442. When wing 442 ofaircraft 400 may be in flight position 444, aircraft 400 may be readyfor flight. For example, wing 102 and wing 104 of FIG. 1 are shown inflight position 444.

Folded position 446 may be a state of wing 442. When wing 442 ofaircraft 400 may be in folded position 446, aircraft 400 may not beready for flight, but a wingspan of aircraft 400 may be smaller than thewingspan of aircraft 400 with wing 442 in flight position 444 and allowuse of aircraft 400 at airports that may require smaller wingspans.

Fixed portion 448 may be an illustrative embodiment of fixed portion 124of wing 102 and may be an embodiment of fixed portion 126 of wing 104 ofFIG. 1 and FIG. 2. Fixed portion 448 of wing 442 may include wing box452 and moveable control surfaces 450. Wing box 452 may be a structuralcomponent from which wing 442 extends. Moveable control surfaces 450 mayinclude flaps that may allow for controlling flight of aircraft 400.

Unfixed portion 454 may be an embodiment of unfixed portion 120 of wing102 and may be an embodiment of unfixed portion 122 of wing 104 of FIG.1 and FIG. 2. Unfixed portion 454 may rotate with respect to fixedportion 448 of wing 442 between flight position 444 of wing 442 andfolded position 446 of wing 442. Unfixed portion 454 of wing 442 mayinclude wingtip 456. Wingtip 456 may not include moveable controlsurfaces 450.

FIG. 5 is a block diagram of a wing fold system 502 in accordance withan illustrative embodiment. Wing fold system 502 may be an illustrativeembodiment of wing fold system 128 and wing fold system 130 of aircraft100 of FIG. 1 and FIG. 2 and wing fold system 458 of aircraft 400 ofFIG. 4. Wing fold system 502 may move wingtip 456 of wing 442 of anaircraft between flight position 510 and folded position 514. Wing foldsystem 502 may be controlled by a wing fold controller 428 of aircraft400.

Wing fold system 502 may include several features, elements, andcomponents, including: status 504, sensors 564, latches 572, actuators576, and joints 578. Wing fold system 458 may move wingtip 456 betweenflight position 444 and folded position 446. Wing fold system 458 may becontrolled by wing fold controller 428.

Status 504 may include wingtip status 506, latch status 522, lock status536, actuator status 550, and aircraft system status 590. Status 504 ofwing fold system 502 may include information related to wing fold system458 of FIG. 4.

Wingtip status 506 may indicate a status of wingtip 456 and may includewingtip position 508, angular position 518, and percentage position 520.Wingtip position 508 may indicate a state of wingtip 456 and may includeflight position 510, transitioning to flight position 512, foldedposition 514, and transitioning to folded position 516. Angular position518 may indicate an angle of wingtip 456 with respect to wing 442.Percentage position 520 may indicate a percentage related to acompletion amount of a transition between flight position 444 and foldedposition 446.

Flight position 510 may indicate that wingtip 456 may be ready forflight. Transitioning to flight position 512 may indicate that wingtip456 may be being moved to flight position 510. Folded position 514 mayindicate that wingtip 456 may be fully folded so as to reduce an overallwingspan of an aircraft. Transitioning to folded position 516 mayindicate that wingtip 456 may be being moved to folded position 514.

Latch status 522 may indicate a status of each latch of latches 572 orof any group of latches 572. Latch status 522 may indicate a status oflatches 572 of wing fold system 502 and may include latch position 524and percentage status 534. Without limitation, latch status 522 may alsoindicate a status for any actuator, wiring, hydraulic power, electricpower, or sensor associated with the particular latch among latches 572.

Latch position 524 may indicate a position of a particular latch amonglatches 572 of wing fold system 502 and may include open position 526,transitioning to open position 528, closed position 530, andtransitioning to closed position 532. Percentage status 534 may indicatea percentage related to a completion amount of a transition between openposition 526 and closed position 530 of the particular latch amonglatches 572.

Open position 526 may indicate that a particular latch among latches 572may be open and wingtip 456 may be not secured. Transitioning to openposition 528 may indicate that the particular latch may be being movedto open position 526 to release wingtip 456 so that it may be folded.Closed position 530 may indicate that the particular latch may be closedand wingtip 456 may be secured. Transitioning to closed position 532 mayindicate that the particular latch may be being moved to closed position530 to secure wingtip 456.

Lock status 536 may indicate a status of each lock of a particular latchamong latches 572 or of any group of locks 574 of latches 572. Lockstatus 536 may indicate a status of locks 574 of latches 572 of wingfold system 502 and may include lock position 538 and percentage status548. Without limitation, lock status 536 may also indicate a status forany actuator, wiring, hydraulic power, electric power, or sensorassociated with a particular latch among locks 574.

Lock position 538 may indicate a position of a lock of wing fold system502 and may include engaged position 540, transitioning to engagedposition 542, disengaged position 544, and transitioning to disengagedposition 546. Percentage status 548 may indicate a percentage related toa completion amount of a transition between engaged position 540 anddisengaged position 544.

Engaged position 540 may indicate that a lock may be engaged with alatch and may indicate that the latch may be secured. Engaged position540 may be associated with wingtip 456 being in flight position 510.Transitioning to engaged position 542 may indicate that locks 574 may betransitioning to engaged position 540 to secure latches 572. Disengagedposition 544 may indicate that a lock 574 may be not engaged withlatches 572 and may indicate that latches 572 may be not secured.Disengaged position 544 may be associated with wingtip 456 being infolded position 514. Transitioning to disengaged position 546 mayindicate that locks 574 may be transitioning to disengaged position 544to release latches 572 so that wingtip 456 may fold.

Actuator status 550 may indicate a status of each actuator of wing foldsystem 502 or of any group of actuators 576. Actuator status 550 mayinclude actuator position 552 and percentage status 562. Withoutlimitation, actuator status 550 may also indicate a status for anycontroller, wiring, hydraulic power, electric power, or sensorassociated with a particular actuator among actuators 576.

Actuator position 552 may indicate a position of an actuator of wingfold system 502 and may include engaged position 554, transitioning toengaged position 556, disengaged position 558, and transitioning todisengaged position 560. Percentage status 562 may indicate a percentagerelated to a completion amount of a transition between engaged position554 and disengaged position 558.

Engaged position 554 may indicate that an actuator of wing fold system502 may be engaged with a lock, latch, or wingtip 456. Transitioning toengaged position 556 may indicate that an actuator may be transitioningto engaged position 554 to actuate a lock, latch, or wingtip 456.Disengaged position 558 may indicate that an actuator may be not engagedwith a lock, latch, or wingtip 456 and may be not providing any forcethereto. Transitioning to disengaged position 560 may indicate that anactuator may be transitioning to disengaged position 558 to release alatch so that wingtip 456 may fold.

Aircraft system status 590 may include a status of any aircraft systemthat may affect wing fold system 502. Without limitation, aircrafthydraulic system, electrical system, wiring, controllers, and motors mayaffect wing fold system 502. Without limitation, a failure of electricalor hydraulic power to a component of wing fold system 502 may affectperformance of a component of wing fold system 502.

Sensors 564 may sense positions and/or loads of components of wing foldsystem 502. Sensors 564 may include: latch sensors 566 that may senseone or more of status and position of a latch; joint sensors 568 thatmay sense one or more of status, position, and load of a joint; actuatorsensors 570 that may sense one or more of status, position, and load ofan actuator; and lock sensors 582 that may sense one or more of statusand position of a lock.

Sensors 564 may also include aircraft system sensors 584, andenvironment sensors 586. Aircraft system sensors 584 may sense one ormore of a status or functionality of various aircraft systems that mayinclude, a hydraulic system, an electrical system, wiring, a flightcontrol system, wing fold controller 428, and/or control center 416.Without limitation, aircraft system sensors 584 may include a pitot orstatic system, a navigation system receiver, a thrust lever position,hydraulic pressure, hydraulic quantity, electrical voltage or current,and solenoid and/or a valve position. Without limitation, aircraftsystem sensors 584 may provide information to determine wind speed,and/or aircraft airspeed or ground speed.

Environment sensors 586 may include sensors that detect conditionspresent around and/or approaching aircraft 400. Conditions presentaround and/or approaching aircraft 400 may include, a physical locationof aircraft 400, weather, a building, an airport structure, and anyobstacle or vehicle around and/or approaching aircraft. Withoutlimitation, environment sensors may include radar, an aircraftair-ground sensor, a Global Positioning System receiver, and/or anAutomatic Dependent Surveillance-Broadcast (ADS-B) receiver.

Latches 572 may latch and secure wingtip 456 in flight position 510.Latches 572 may include locks 574 that may lock latches 572 in closedposition 530 to secure latches 572 and wingtip 456 in flight position510.

Actuators 576 may actuate various components of wing fold system 502.Actuators 576 may include a wingtip actuator that may transition wingtip456 between flight position 510 and folded position 514. The wingtipactuator may move wingtip 456 by moving unfixed portion 454.

The wingtip actuator may include brake 580. Brake 580 may be any type ofbrake as may be known in the art for inhibiting motion of wingtip 456.Without limitation, brake 580 may be a pressure-off brake that may bespring biased and inhibit motion of wingtip actuator unless hydraulicpressure may be present on the brake. Thus, hydraulic power may bewithheld from the wingtip actuator, and the brake may inhibit movementof the wingtip actuator while hydraulic pressure may be removed fromcomponents of wing fold system 502 such as but not limited to thewingtip actuator.

Brake 580 may provide redundancy to ensure that when wingtip position508 may be in flight position 510 or in folded position 514, thatactuator will not attempt to move wingtip 456 without a command. Brake580 may provide redundancy to ensure that hydraulic fluid is not in ahydraulic actuator except when actuation of the actuator is commanded.Brake 580 may also be activated by wing fold controller 428 based onanother status 504.

Actuators 576 may also include a latch actuator that may transitionlatches 572 between open position 526 and closed position 530. Actuators576 may also include a lock actuator that may transition locks 574 oflatches 572 between engaged position 540 and disengaged position 544.

Joints 578 may allow movement of wingtip 456 of a wing with respect towing 442. Wingtip 456 of wing 442 may move, rotate, or fold with respectto wing 442 via joints 578. Joints 578 may be located on fixed portion448 and/or unfixed portion 454 and may connect fixed portion 448 andunfixed portion 454.

FIG. 6 is a diagram of a wing embodying a wing fold system in accordancewith an illustrative embodiment. FIG. 6 depicts a wing embodying a wingfold system controlled by a wing fold controller. Wing 602 may be anillustrative embodiment of wing 442 of aircraft 400 of FIG. 4 and wing102/104 of aircraft 100 of FIG. 1. FIG. 6 depicts an underside of wing602 in a folded position. Wing 602 may include fixed portion 604,unfixed portion 606, and wing fold system 608.

Fixed portion 604 may be an embodiment of fixed portion 124 of wing 102and fixed portion 126 of wing 104 of FIG. 1 and FIG. 2. Fixed portion604 may be an embodiment of fixed portion 448 of wing 442 of FIG. 4.Fixed portion 604 of wing 602 may include a wing box and moveablecontrol surfaces (not shown).

Unfixed portion 606 may be an embodiment of unfixed portion 120 of wing102, unfixed portion 122 of wing 104 of FIG. 1, and unfixed portion 454of wing 442 of FIG. 4. Unfixed portion 606 may rotate with respect tofixed portion 604 of wing 602 between a flight position and a foldedposition. Unfixed portion 606 of wing 602 may include wingtip 618.Wingtip 618 may not include moveable control surfaces. In alternativeembodiments, a control surface may be included in wingtip 618.

Wing fold system 608 may be an embodiment of a wing fold system of awing of an aircraft, such as wing 102 and wing 104 of aircraft 100 ofFIG. 1 and FIG. 2. Wing fold system 608 may be an embodiment of wingfold system 458 of wing 442 of aircraft 400 of FIG. 4. Wing fold system608 may be an embodiment of wing fold system 502 of FIG. 5. Wing foldsystem 608 may move unfixed portion 606 with respect to fixed portion604 in response to a wing fold controller, such as wing fold controller428 of FIG. 4. Wing fold system 608 may include latches 612, locks 614,and actuator 616.

Latches 612 may latch and secure wingtip 618 in a flight position. Locks614 may engage latches 612 when latches 612 may be in a closed positionto prevent latches 612 from opening while wingtip 618 may be in flightposition. Wingtip actuator 616 may actuate wingtip 618 to transitionwingtip 618 between the flight position and a folded position.

FIG. 7 a and FIG. 7 b are a flowchart of a method 700 of a wing foldcontroller in accordance with an illustrative embodiment. Method 700shown in FIG. 7 a and FIG. 7 b may be implemented using aircraft 100 ofFIG. 1 and FIG. 2. The method shown in FIG. 7A and FIG. 7B may beimplemented by a processor, such as processor unit 1004 of FIG. 10. Themethod shown in FIG. 7A and FIG. 7B may be a variation of the processesshown in FIG. 1 through FIG. 6 and FIG. 8 through FIG. 10. Although theoperations presented in FIG. 7A and FIG. 7B are described as beingperformed by a “process,” the operations are being performed by at leastone tangible processor or using one or more physical devices, asdescribed elsewhere herein. The term “process” also may include computerinstructions stored on a non-transitory computer readable storagemedium.

Method 700 may begin as the method may receive a status of at least oneof an aircraft and a wing fold system of the aircraft by the wing foldcontroller of the aircraft (operation 702). Next, the method may receivea command by the wing fold controller of the aircraft (operation 704).Next, the method may optionally generate the command as an automatedcommand by the wing fold controller in response to receiving the status(operation 706).

A wing controller may generate an automated command to set a wing to afolded position when the status indicates the aircraft may be on orapproaching a taxiway. A wing controller may generate an automatedcommand to set the wing to the flight position when the status indicatesthe aircraft may be on a runway, such as without limitation aftertouchdown, or when using a runway to taxi the aircraft.

Based on an aircraft's location relative to a taxiway and/or a runway, awarning may be provided to the crew to change a position of a wingtip.Typically, the wingtip position may be changed while the aircraft may beon the ground. In a non-limiting example, an aircraft may have itswingtips in a folded position while at the gate, and in a flightposition when approaching a runway for takeoff. A command to move thewingtip to the flight position may be automatically generated. Thecommand to move the wingtip to the flight position may be based on theaircraft's position relative to the taxiway and/or the runway.

After aircraft 400 touchdown on landing, wingtip 456 may be folded.Command 430 to fold wingtip 456 may change the position of wingtip 456based on the aircraft's position relative to the taxiway or the runway.Command 430 to fold wingtip 456 may be automatically generated.

Next, the method may operate the wing fold system of the aircraft basedon the command and the status (operation 708). A wing fold controllermay operate the wing fold system of the aircraft based on the commandreceived in operation 704 and the status received in operation 702.Operation of the wing fold system by the wing fold controller may be viaelectrical, optical, mechanical, pneumatic, or hydraulic connectionsbetween the wing fold controller and the wing fold system and itsvarious components.

Next, the method may transition a wingtip of a wing of the aircraft toone of a flight position of the wing and a folded position of the wingby an actuator of the wing fold system in response to operating the wingfold system (operation 710). Transitioning of the wingtip may take placeby rotating or folding the wingtip at a joint shared by the wingtip anda fixed portion of the wing via the actuator. The actuator may bemechanically connected directly to the wingtip, or through a series oflinks and joints to establish the mechanical connection.

Next, the method may display the status of the wing fold system on adisplay (operation 712). The display may show any combination of thestatus received in operation 702, the command received in operation 704,and any other status related to a wing fold system.

Next, the method may transition a latch of the wing fold system of theaircraft to one of an open position and a closed position after thewingtip transitions to the flight position by a latch actuator(operation 714). The latch may secure the wingtip in the flight positionso as to prevent movement of the wingtip during flight of the aircraft.

Next, the method may transition a lock of the latch of the wing foldsystem of the aircraft to one of an engaged position and a disengagedposition to prevent movement of the latch and the wingtip by a lockactuator (operation 716). Next, the method may determine if the lock ofthe latch of the wing fold system may be operational via the actuator bythe wing fold controller (operation 718). In so doing, the wing foldcontroller may cross check the functionality of components of a wingfold system.

Next, the method may attempt to move the wingtip via the actuator afterthe lock of the latch of the wing fold system may be in the engagedposition (operation 720). If the lock and latch are working properly,the wingtip may not move. If either one or both of the lock and thelatch are not working properly, the wingtip may move. Being able to movethe wingtip after the lock and the latch are engaged indicates that thewing fold system may not be working properly.

Next, the method may communicate a warning in response to attempting tomove the wingtip after the lock may be in the engaged position(operation 722). The warning may indicate that the aircraft may not beready for flight and may be in need of maintenance.

Next, the method may determine that the status prevents the command(operation 724). When an aircraft may be in flight, the wing controllermay determine that a command to fold a wingtip may be prevented by theaircraft's status of being in flight.

Next, the method may prevent transitioning the wingtip when the statusprevents the command (operation 726). When an aircraft may be in flight,the wing controller may prevent executing a command to fold the wingtipsince the aircraft may be in flight. Additionally, when the status wouldprevent the command, an indication of such may be given to a crew memberon a display of the aircraft.

Next, the method may communicate a warning in response to receiving thestatus when the status indicates a location of the aircraft requiring adifferent position of the wingtip (operation 728). The warning may becommunicated when the status indicates the wingtip may be in the flightposition and the location indicates that the aircraft may be situated onor approaching a taxiway, a gate, or any location that may require thewingspan to be reduced. The warning may be communicated when the statusindicates the wingtip may be in the folded position and the locationindicates that the aircraft may be on a runway. Method 700 may terminatethereafter.

FIG. 8 is a flowchart of a method of manufacturing a commercialaircraft. Illustrative embodiments of the disclosure may be described inthe context of aircraft manufacturing and service method 800 as depictedin FIG. 8 and aircraft 900 as shown in FIG. 9. Turning first to FIG. 8,an illustration of an aircraft manufacturing and service method isdepicted in accordance with an illustrative embodiment. Duringpre-production, aircraft manufacturing and service method 800 mayinclude specification and design 802 of aircraft 900 in FIG. 9 andmaterial procurement 804.

During production, component and subassembly manufacturing 806 andsystem integration 808 of aircraft 900 in FIG. 9 takes place.Thereafter, aircraft 900 in FIG. 9 may go through certification anddelivery 810 in order to be placed in service 812. While in service 812by a customer, aircraft 900 in FIG. 9 may be scheduled for routinemaintenance and service 814, which may include modification,reconfiguration, refurbishment, and other maintenance or service.

Each of the processes of aircraft manufacturing and service method 800may be performed or carried out by a system integrator, a third party,and/or an operator. In these examples, the operator may be a customer.For the purposes of this description, a system integrator may include,without limitation, any number of aircraft manufacturers andmajor-system subcontractors; a third party may include, withoutlimitation, any number of vendors, subcontractors, and suppliers; and anoperator may be an airline, a leasing company, a military entity, aservice organization, and so on.

FIG. 9 is a block diagram of a commercial aircraft. Aircraft 900 may beproduced by aircraft manufacturing and service method 800 in FIG. 8 andmay include airframe 902 with plurality of systems 904 and interior 906.Examples of systems 904 include one or more of propulsion system 908,electrical system 910, hydraulic system 912, and environmental system914. Any number of other systems may be included. Although an aerospaceexample is shown, different illustrative embodiments may be applied toother industries, such as the automotive industry.

Apparatuses and methods embodied herein may be employed during at leastone of the stages of aircraft manufacturing or service method 800 inFIG. 8. In one illustrative example, components or subassembliesproduced in component and subassembly manufacturing 806 in FIG. 8 may befabricated or manufactured in a manner similar to components orsubassemblies produced while aircraft 900 may be in service 812 in FIG.8. As yet another example, one or more apparatus embodiments, methodembodiments, or a combination thereof may be utilized during productionstages, such as component and subassembly manufacturing 806 and systemintegration 808 in FIG. 8. One or more apparatus embodiments, methodembodiments, or a combination thereof may be utilized while aircraft 900may be in service 812 and/or during maintenance and service 814 in FIG.8. The use of a number of the different illustrative embodiments maysubstantially expedite the assembly of and/or reduce the cost ofaircraft 900.

FIG. 10 is an illustration of a data processing system, in accordancewith an illustrative embodiment. Data processing system 1000 in FIG. 10may be an example of a data processing system that may be used toimplement the illustrative embodiments, such as aircraft 100 of FIG. 1or FIG. 2, or any other module or system or method disclosed herein. Inthis illustrative example, data processing system 1000 includescommunications fabric 1002, which provides communications betweenprocessor unit 1004, memory 1006, persistent storage 1008,communications unit 1010, input/output (I/O) unit 1012, and display1014.

Processor unit 1004 serves to execute instructions for software that maybe loaded into memory 1006. Processor unit 1004 may be a number ofprocessors, a multi-processor core, or some other type of processor,depending on the particular implementation. A number, as used hereinwith reference to an item, means one or more items. Further, processorunit 1004 may be implemented using a number of heterogeneous processorsystems in which a main processor may be present with secondaryprocessors on a single chip. As another illustrative example, processorunit 1004 may be a symmetric multi-processor system containing multipleprocessors of the same type.

Memory 1006 and persistent storage 1008 may be embodiments of storagedevices 1016. A storage device may be any piece of hardware that may becapable of storing information, such as, for example, withoutlimitation, data, program code in functional form, and/or other suitableinformation either on a temporary basis and/or a permanent basis.Storage devices 1016 may also be referred to as computer readablestorage devices in these examples. Memory 1006, in these examples, maybe, for example, a random access memory or any other suitable volatileor non-volatile storage device. Persistent storage 1008 may take variousforms, depending on the particular implementation.

For example, persistent storage 1008 may contain one or more componentsor devices. For example, persistent storage 1008 may be a hard drive, aflash memory, a rewritable optical disk, a rewritable magnetic tape, orsome combination of the above. The media used by persistent storage 1008also may be removable. For example, a removable hard drive may be usedfor persistent storage 1008.

Communications unit 1010, in these examples, may provide forcommunications with other data processing systems or devices. In theseexamples, communications unit 1010 may be a network interface card.Communications unit 1010 may provide communications through the use ofeither or both physical and wireless communications links.

Input/output (I/O) unit 1012 may allow for input and output of data withother devices that may be connected to data processing system 1000.Without limitation, input/output (I/O) unit 1012 may provide aconnection for user input through a keyboard, a mouse, a processor,lever, or switch that may be in a control center that may be in acockpit or in a maintenance facility, and/or some other suitable inputdevice. Further, input/output (I/O) unit 1012 may send output to aprinter. Display 1014 may provide a mechanism to display information toa user.

Instructions for the operating system, applications, and/or programs maybe located in storage devices 1016, which are in communication withprocessor unit 1004 through communications fabric 1002. In theseillustrative examples, the instructions are in a functional form onpersistent storage 1008. These instructions may be loaded into memory1006 for execution by processor unit 1004. The processes of thedifferent embodiments may be performed by processor unit 1004 usingcomputer implemented instructions, which may be located in a memory,such as memory 1006.

These instructions are referred to as program code, computer usableprogram code, or computer readable program code that may be read andexecuted by a processor in processor unit 1004. The program code in thedifferent embodiments may be embodied on different physical or computerreadable storage media, such as memory 1006 or persistent storage 1008.

Program code 1018 may be located in a functional form on computerreadable media 1020 that may be selectively removable and may be loadedonto or transferred to data processing system 1000 for execution byprocessor unit 1004. Program code 1018 and computer readable media 1020form computer program product 1022 in these examples. In one example,computer readable media 1020 may be computer readable storage media 1024or computer readable signal media 1026. Computer readable storage media1024 may include, for example, an optical or magnetic disk that may beinserted or placed into a drive or other device that may be part ofpersistent storage 1008 for transfer onto a storage device, such as ahard drive, that may be part of persistent storage 1008. Computerreadable storage media 1024 also may take the form of a persistentstorage, such as a hard drive, a thumb drive, or a flash memory, thatmay be connected to data processing system 1000. In some instances,computer readable storage media 1024 may not be removable from dataprocessing system 1000.

Alternatively, program code 1018 may be transferred to data processingsystem 1000 using computer readable signal media 1026. Computer readablesignal media 1026 may be, for example, a propagated data signalcontaining program code 1018. For example, computer readable signalmedia 1026 may be an electromagnetic signal, an optical signal, and/orany other suitable type of signal. These signals may be transmitted overcommunications links, such as wireless communications links, opticalfiber cable, coaxial cable, a wire, and/or any other suitable type ofcommunications link. In other words, the communications link and/or theconnection may be physical or wireless in the illustrative examples.

In some illustrative embodiments, program code 1018 may be downloadedover a network to persistent storage 1008 from another device or dataprocessing system through computer readable signal media 1026 for usewithin data processing system 1000. For instance, program code stored ina computer readable storage medium in a server data processing systemmay be downloaded over a network from the server to data processingsystem 1000. The data processing system providing program code 1018 maybe a server computer, a client computer, or some other device capable ofstoring and transmitting program code 1018.

The different components illustrated for data processing system 1000 arenot meant to provide architectural limitations to the manner in whichdifferent embodiments may be implemented. The different illustrativeembodiments may be implemented in a data processing system includingcomponents in addition to or in place of those illustrated for dataprocessing system 1000. Other components shown in FIG. 10 can be variedfrom the illustrative examples shown. The different embodiments may beimplemented using any hardware device or system capable of runningprogram code. As one example, the data processing system may includeorganic components integrated with inorganic components and/or may becomprised entirely of organic components excluding a human being. Forexample, a storage device may be comprised of an organic semiconductor.

In another illustrative example, processor unit 1004 may take the formof a hardware unit that has circuits that are manufactured or configuredfor a particular use. This type of hardware may perform operationswithout needing program code to be loaded into a memory from a storagedevice to be configured to perform the operations.

For example, when processor unit 1004 takes the form of a hardware unit,processor unit 1004 may be a circuit system, an application specificintegrated circuit (ASIC), a programmable logic device, or some othersuitable type of hardware configured to perform a number of operations.With a programmable logic device, the device may be configured toperform the number of operations. The device may be reconfigured at alater time or may be permanently configured to perform the number ofoperations. Examples of programmable logic devices include, for example,a programmable logic array, programmable array logic, a fieldprogrammable logic array, a field programmable gate array, and othersuitable hardware devices. With this type of implementation, programcode 1018 may be omitted because the processes for the differentembodiments are implemented in a hardware unit.

In still another illustrative example, processor unit 1004 may beimplemented using a combination of processors found in computers andhardware units. Processor unit 1004 may have a number of hardware unitsand a number of processors that are configured to run program code 1018.With this depicted example, some of the processes may be implemented inthe number of hardware units, while other processes may be implementedin the number of processors.

As another example, a storage device in data processing system 1000 maybe any hardware apparatus that may store data. Memory 1006, persistentstorage 1008, and computer readable media 1020 are examples of storagedevices in a tangible form.

In another example, a bus system may be used to implement communicationsfabric 1002 and may be comprised of one or more buses, such as a systembus or an input/output bus. Of course, the bus system may be implementedusing any suitable type of architecture that provides for a transfer ofdata between different components or devices attached to the bus system.Additionally, a communications unit may include one or more devices usedto transmit and receive data, such as a modem or a network adapter.Further, a memory may be, for example, memory 1006, or a cache, such asfound in an interface and memory controller hub that may be present incommunications fabric 1002.

Data processing system 1000 may also include at least one associativememory (not shown in FIG. 10). Associative memory may be incommunication with communications fabric 1002. Associative memory mayalso be in communication with, or in some illustrative embodiments, beconsidered part of storage devices 1016. The different illustrativeembodiments can take the form of an entirely hardware embodiment, anentirely software embodiment, or an embodiment containing both hardwareand software elements. Some embodiments are implemented in software,which includes but may be not limited to forms, such as, for example,firmware, resident software, and microcode.

Furthermore, the different embodiments can take the form of a computerprogram product accessible from a computer usable or computer readablemedium providing program code for use by or in connection with acomputer or any device or system that executes instructions. For thepurposes of this disclosure, a computer usable or computer readablemedium can generally be any tangible apparatus that can contain, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.

The computer usable or computer readable medium can be, for example,without limitation an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, or a propagation medium. Non-limitingexamples of a computer readable medium include a semiconductor or solidstate memory, magnetic tape, a removable computer diskette, a randomaccess memory (RAM), a read-only memory (ROM), a rigid magnetic disk,and an optical disk. Optical disks may include compact disk—read onlymemory (CD-ROM), compact disk—read/write (CD-R/W), and DVD.

Further, a computer usable or computer readable medium may contain orstore a computer readable or usable program code such that when thecomputer readable or usable program code may be executed on a computer,the execution of this computer readable or usable program code causesthe computer to transmit another computer readable or usable programcode over a communications link. This communications link may use amedium that may be, for example without limitation, physical orwireless.

A data processing system suitable for storing and/or executing computerreadable or computer usable program code will include one or moreprocessors coupled directly or indirectly to memory elements through acommunications fabric, such as a system bus. The memory elements mayinclude local memory employed during actual execution of the programcode, bulk storage, and cache memories which provide temporary storageof at least some computer readable or computer usable program code toreduce the number of times code may be retrieved from bulk storageduring execution of the code.

Input/output or I/O devices can be coupled to the system either directlyor through intervening I/O controllers. These devices may include, forexample, without limitation, keyboards, touch screen displays, andpointing devices. Different communications adapters may also be coupledto the system to enable the data processing system to become coupled toother data processing systems or remote printers or storage devicesthrough intervening private or public networks. Non-limiting examples ofmodems and network adapters are just a few of the currently availabletypes of communications adapters.

Thus, illustrative embodiments above may describe a method ofcontrolling folding of a wing. The method may include: receiving astatus, of at least one of: an aircraft, and a wing fold system of theaircraft, by a wing fold controller of the aircraft; receiving acommand, by the wing fold controller, in response to receiving thestatus; operating the wing fold system, by the wing fold controller,based on the command and the status. The method may also includetransitioning, via a wingtip actuator of the wing fold system, a wingtipof the wing of the aircraft to one of: a flight position of the wing,and a folded position of the wing, in response to operating the wingfold system by the wing fold controller.

The illustrative embodiments for a method of controlling folding of awing may also include that the status may indicate the aircraft is on ataxiway and the command directs the wing to the folded position; andwherein the status may indicate the aircraft is on a runway and thecommand directs the wing to the flight position.

Further, the method may include: displaying the status of the wing foldsystem on a display; or determining, via the wing fold controller, if alock of the wing fold system is operational via attempting to move thewingtip via the wingtip actuator after the lock of the wing fold systemis in an engaged position; and communicating a warning in response toattempting to move the wingtip after the lock is in the engagedposition.

The illustrative embodiments for a method of controlling folding of awing may also include determining, via the wing fold controller, thatthe status prevents the command; and preventing, via the wing foldcontroller, the wingtip actuator from transitioning the wingtip when thestatus prevents the command. The illustrative embodiments for a methodof controlling folding of a wing may also include transitioning, via alatch actuator, a latch of the wing fold system of the aircraft to oneof an open position and a closed position after the wingtip transitionsto the flight position; and transitioning, via a lock actuator, a lockof the latch of the wing fold system of the aircraft to one of: anengaged position, and a disengaged position that may prevent movementof: the latch, and the wingtip.

The illustrative embodiments for a method of controlling folding of awing may also include communicating a warning in response to receivingthe status, when the status may indicate that a location of the aircraftmay require a different position of the wingtip, wherein the status mayindicate that the wingtip is in the flight position, and that thelocation of the aircraft is one of: on a taxiway, and at a gate; andwherein the status indicates that the wingtip is in the folded position,and the location of the aircraft is on a runway.

The embodiments above may also describe an apparatus configured tocontrol a wing fold system of a wing of an aircraft. The apparatus mayinclude a wing fold controller configured to: receive a status of atleast one of: the aircraft, and the wing fold system of the aircraft;receive a command based on receiving the status; and operate the wingfold system of the aircraft based on the command and the status; and awingtip actuator configured to transition, in response to the wing foldcontroller, a wingtip of the wing of the aircraft to one of: a flightposition and a folded position. The apparatus may also be configuredwherein the status indicates that the aircraft is at least one of: on ataxiway, and rolling toward the taxiway, and the command directs thewing to the folded position; and wherein the status indicates theaircraft is at least one of: on a runway, and rolling toward the runway,and the command directs the wing to the flight position.

The apparatus may also include a display configured to display thestatus of the wing fold system, and/or the wing fold controllerconfigured to: determine that a lock of the wing fold system isoperational via an attempt to move the wingtip, via the wingtipactuator, after the lock of a latch of the wing fold system is in anengaged position, and communicate a warning in response to attempting tomove the wingtip after the lock is in the engaged position. Theapparatus may also include the wing fold controller configured to:determine that the status prevents the command, and preventtransitioning the wingtip when the status prevents the command.

The apparatus may also include a latch actuator configured to transitiona latch of the wing fold system of the aircraft to one of: an openposition, and a closed position, after the wingtip transitions to theflight position; and a lock actuator configured to transition a lock ofthe wing fold system of the aircraft to one of: an engaged position, anda disengaged position, and prevent movement of the latch and thewingtip. The apparatus may also include the wing fold controllerconfigured to communicate, when the status may indicate that a locationof the aircraft may require a different position of the wingtip, awarning in response to receiving the status, and the status indicates atleast one of: that the wingtip is in the flight position, and that theaircraft is one of: on a taxiway, at a gate, approaching any obstacle orvehicle that the wing fold controller predicts to contact the wingtip,and approaching a taxiway; and that the wingtip is in the foldedposition and at least one of: on a runway, and rolling toward a runway.

Illustrative embodiments above may also describe an aircraft thatincludes a computer that includes: a bus, a processor connected to thebus, and a memory connected to the bus, the memory storing a programcode. The program code, when executed by the processor, may perform acomputer-implemented method. The program code is: configured to receivea status of at least one of: the aircraft, and a wing fold system of theaircraft, by a wing fold controller of the aircraft; configured toreceive a command, by the wing fold controller of the aircraft, inresponse to receiving the status; configured to, using the processor,operate the wing fold system of the aircraft, via the wing foldcontroller, based on the command and the status; and configured to,using the processor, transition a wingtip of a wing of the aircraft toone of: a flight position and a folded position via a wingtip actuatorof the wing fold system.

Illustrative embodiments of the aircraft may also include the statusindicating that the aircraft is at least one of: on a taxiway, androlling toward the taxiway, and the command may direct the wing to thefolded position; and wherein the status may indicate the aircraft is atleast one of: on a runway, and rolling toward the runway, and thecommand directs the wing to the flight position. Illustrativeembodiments of the may also include the program code configured use theprocessor to: determine, via the wingtip actuator by the wing foldcontroller, if a lock of the wing fold system is operational; attempt tomove the wingtip via the wingtip actuator after the lock of the wingfold system is in an engaged position; and, communicate a warning, inresponse to an attempt to move the wingtip after the lock is in theengaged position wherein at least one of status and position of the lockis determined via sensing by at least one lock sensor.

Illustrative embodiments of the aircraft may also include program codeconfigured to use the processor to: determine that the status preventsthe command; and prevent transitioning the wingtip when the statusprevents the command.

Illustrative embodiments may recognize and take into account that anunfixed portion of a wing is connected to and rotate about a hinge on afixed portion of the wing. Illustrative embodiments may recognize andtake into account that a hinge on the fixed portion of the wing islocated at various positions on the fixed portion and on the unfixedportion, such as without limitation, a top side of the wing, a bottomside of the wing, and near a center of a thickness of the wing.Illustrative embodiments may recognize and take into account thatlocating the hinge near a top side or near a bottom side of the wing mayresult in the hinge that protrudes beyond the profile of the wing.

A hinge, or components related to the hinge, that may protrude, beyond aprofile of the wing without a hinge, may require a fairing to reduceexposure of the hinge to the environment and airstream, and aerodynamicdrag produced by the hinge. While a fairing may reduce the drag causedby an exposed hinge, the fairing may increase the weight of the wing anddrag produced by the wing as compared to a wing that has no fairing andno exposed hinge. Thus, as shown without limitation in U.S. applicationSer. No. 13/664,371, which is hereby fully incorporated herein, it maybe desirable to have a hinge located fully within the wing, such that nofairing may be needed to add the hinge to the wing. Similarly, it may bedesirable to have components associated with the hinge and activation offolding the wing, such as without limitation an angle gearbox, a torquetube, a torque box, a lug, a bushing, a latch, a lock, and anyassociated sensor, located fully within the wing, such that no fairingmay be needed to add the hinge to the wing.

Alternatively, in place of a rotating motion, a sliding or a telescopictranslation may be used to extend an unfixed portion of a wing. In thatconfiguration, motors and devices configured to translate the wingunfixed portion may be used in place of the angle gearbox, the torquetube, and/or the torque box to facilitate translating the unfixedportion of the wing instead of rotating the unfixed portion of the wing.

Further, illustrative embodiments may recognize and take into accountthat it may be desirable for the hinge and the wingtip actuator thattransitions an unfixed portion of a wing between a folded position, oron-ground position, and a flight position, and all components associatedtherewith, to occupy a minimum amount of space within the wing and add aminimum amount of weight to the wing. Currently, downsizing a motor of agiven design typically reduces the power output from the motor. Thus,illustrative embodiments may recognize and take into account thatreducing a size of the wingtip actuator may limit an amount of poweravailable from the wingtip actuator. Thus, it may be desirable toincrease power available from a wingtip actuator of any given size, orto reduce the amount of power needed to transitions an unfixed portionof a wing between a folded, or on-ground position and a flight position.Thereby, a wing containing wing fold system 1100 may be sized such thatno component of wing fold system 1100 may require a fairing that expandsa profile of the wing.

Referring now to FIG. 11, FIG. 11 is a plan view diagram of a wing foldsystem, in accordance with an illustrative embodiment. Morespecifically, wing fold system 1100 may include wing fold actuator 1102,torque tube 1104, angle gearbox 1106, torque tube 1108, power drive unit1110, control module 1112, isolation device 1114, power system 1116,flight controls computer 1118, aircraft control panel 1120, lockactuator 1122, lock 1124, fixed portion 1126, unfixed portion 1128, foldaxis 1130, and analog-to-digital converter unit 1132. Wing fold system1100 may be a schematic view of an illustrative embodiment of wing foldsystem 502 as shown in FIG. 5. Although wing fold system 1100 shows asingle wing, power system 1116 and flight controls computer 1118 may beconnected to similar features in another wing as those shown for thewing in wing fold system 1100 of FIG. 11.

Power system 1116 may supply power to power drive unit 1110. Powersystem 1116 may include an electric, a pneumatic, and/or a hydraulic,power supply or any other source that may drive wing fold actuator 1102.Power drive unit 1110 may convert power from control module into a forcethat drives wing fold actuator 1102. Without limitation, when wing foldactuator 1102 may be a geared rotary actuator, the force that driveswing fold actuator 1102 may be a torque.

Power drive unit 1110 may include a motor and a brake. Withoutlimitation, the brake may include a configuration that locks out motionof power drive unit 1110. The motor and the brake may be compatible withpower system 1116. In other words, without limitation, if power system1116 may be for an electrical power source, then the motor may bepowered by electricity. If power system 1116 may be for a pneumaticsource, then the motor may be powered by pneumatics. Without limitation,wing fold actuator 1102 may be a geared rotary actuator or may beconfigured to drive a sliding or a telescoping configuration for unfixedportion 1128.

Power drive unit 1110 may be controlled by control module 1112. Controlmodule 1112 may regulate power supply from power system 1116 to powerdrive unit 1110. Control module 1112 may be controlled by flightcontrols computer 1118. Sensors for status and/or position of componentsof wing fold system may send information to flight controls computer1118. Information from components of wing fold system 1100 may be sentto flight controls computer 1118 via analog-digital converter unit 1132.

Analog-digital converter unit 1132 may convert analog signals to digitalsignals and/or digital signals to analog signals. Thus, analog signalspresent at control module 1112 may be converted to digital signals atanalog-digital converter unit 1132. Transmission of information, presentin control module 1112, on status and/or position of components of wingfold system 1100, may be transmitted as digital signals to flightcontrols computer 1118 via analog-digital converter unit 1132. Hence,use of analog-digital converter unit 1132 may allow for wirelesstransmission of digital signals between control module 1112 and flightcontrols computer 1118, and/or transmission of digital signals betweencontrol module 1112 and flight controls computer 1118 upon some numberof wires, wherein the number may be one. Flight controls computer 1118can command and communicate with control module control module 1112, andcomponents connected thereto, without the need for wiring bundlesconnecting control module 1112 and flight controls computer flightcontrols computer 1118. Thereby the weight added and/or space used bywiring bundles for communication and/or command and control betweencontrol module 1112 and flight controls computer 1118 may be eliminated.Hence, inclusion of analog-digital converter unit 1132 may reduce theweight of wing fold system 1100 and/or a size and/or a profile of a wingcontaining wing fold system 1100. Reduction of the weight of wing foldsystem 1100 and/or a size and/or a profile of a wing containing wingfold system 1100 may increase a performance and/or a fuel efficiency ofthe aircraft containing wing fold system 1100. Thereby, a wingcontaining wing fold system 1100 may be sized such that no component ofwing fold system 1100 may require a fairing that expands a profile ofthe wing.

Inputs may be received in flight controls computer 1118 from controlpanel 1120. Without limitation, control panel 1120 may be in a cockpitof the aircraft containing wing fold system 1100, or control panel 1120may be located in another part of the aircraft containing wing foldsystem 1100, or outside of the aircraft containing wing fold system1100. Control panel 1120 may be a network of controls located bothinside and outside of the aircraft containing wing fold system 1100.Flight controls computer 1118 may also send information and/or alertsregarding without limitation a function, a status, and/or a position ofa component of wing fold system 1100, wherein the component may includewithout limitation unfixed portion 1128, wing fold actuator 1102, and/orlock actuator 1122.

When wing fold actuator 1102 may be a geared rotary actuator, withoutlimitation power drive unit 1110 may convert power from control module1112 to torque that may drive wing fold actuator 1102 via torque tube,1108, angle gearbox 1106, and torque tube 1104 being connected to wingfold actuator 1102. Wing fold actuator 1102 may be the torque pathbetween the unfixed portion 1128 and fixed portion fixed portion 1126 ofa wing as shown in FIG. 11. When wing fold actuator 1102 may activateunfixed portion 1128 via a sliding or a telescopic motion, wing foldactuator 1102 may direct a translation of unfixed portion 1128 that maynot require torque tube, 1108, angle gearbox 1106, and torque tube 1104being connected to wing fold actuator wing fold actuator 1102.

Wing fold actuator 1102 may be connected to fixed portion 1126 and tounfixed portion 1128 such that wing fold actuator 1102 may be centeredabout fold axis 1130. Fold axis 1130 may be substantially aligned with acenterline axis of wing fold actuator 1102. Fold axis fold axis 1130 maybe an axis about which unfixed portion 1128 may rotate whentransitioning between flight position 510 and folded position 514.Alternatively, when unfixed portion 1128 may not rotate, but maytelescope or translate into fixed portion 1126, then fold axis 1130 maymark an axis of alignment for unfixed portion 1128 and fixed portion1126 when unfixed portion 1128 may be in flight position 510.

Wing fold system 1100 may include more than one set of latches, such aswithout limitation latches 572 as shown in FIG. 5. Thus, threerepresentations, identical to lock actuator 1122, and lock 1124, areshown in fixed portion 1126 of the wing to indicate that more than onelock actuator 1122, and thus more than one lock 1124 may be used tosecure unfixed portion 1128 in flight position, such as withoutlimitation flight position 510 as shown in FIG. 5.

Wing fold actuator 1102 may be sufficiently powerful to move unfixedportion 1128 to an on-ground position, flight position 510, and anyposition between the on-ground position and flight position 510, andhold unfixed portion 1128 in that position while an aircraft unfixedportion 1128 may be connected to may be on the ground. On-groundposition for unfixed portion 1128 may include folded position 514 asdescribed above at least for FIG. 5. On-ground position may also includea position for unfixed portion 1128 that may reduce a wing span for anaircraft such as reduced wingspan 202 as shown in FIG. 2 as compared towingspan 132 as shown in FIG. 1. Alternatively, without limitation,unfixed portion 1128 may be configured to translate and/or telescope outto flight position 510 from within or over fixed portion 1126. In suchan illustrative embodiment (not shown) on-ground position would beanalogous to folded position 514, but instead of reducing wingspan 132by folding unfixed portion 1128, wingspan 132 may be reduced to wingspan202 by retracting unfixed portion 1128 to within or over fixed portion1126.

Without limitation, on-ground position may refer to a position whereunfixed portion 1128 may be secured such that a wingspan of an aircraftmay be reduced such that the aircraft wingspan may be short enough to bewithin restrictions at given airport for aircraft moving the aircrafton-ground at the airport. As such, wing fold actuator 1102 may need toovercome environmental forces acting upon unfixed portion 1128, any liftand drag forces acting on unfixed portion 1128, and forces generated onunfixed portion 1128 by the aircraft moving across the ground.Environmental forces may include without limitation wind. Forcesgenerated on unfixed portion 1128 by the aircraft moving across theground may include without limitation forces resulting surfaceimperfections and varying operator techniques.

Control module 1112 may also control a second set of locks and lockactuators that are not show, which function to lock unfixed portion 1128into latches holding unfixed portion 1128 in the on-ground position asshown in FIG. 5. Thus, the illustrative embodiments above may show asystem for preparing an aircraft with a folding wing for takeoff.

For take-off, flight controls computer 1118 may receive a command toextend unfixed portion 1128 by moving wing fold actuator 1102 once anairplane containing wing fold system 1100 may be a position within anairport environment that can accommodate the increased wingspan. Wingfold system 1100 may proceed through a number of steps described below.

When preparing for takeoff, control panel 1120 may generate a commandreceived by flight controls computer 1118 for unfixed portion 1128 toextend to flight position 510, as shown in FIG. 5. The command forunfixed portion 1128 to extend to flight position flight position 510may be input by an operator or by an automatic system. The automaticsystem may issue the command based upon a position of the aircraftcontaining wing fold system 1100. The operator command input may bereceived at control panel 1120 from an operator inside and/or outsidethe aircraft containing wing fold system 1100. An indication may beprovided using control panel 1120 that unfixed portion 1128 may be “intransit.” Isolation device 1114 may then open and power system 1116 maysupply power to control module 1112.

Isolation device 1114 may be any device that may isolate power system1116 from control module 1112 and power drive unit 1110. Withoutlimitation when power system 1116 may be a hydraulic power source or apneumatic power source, isolation device 1114 may be a valve. Withoutlimitation when power system 1116 may be an electrical source, isolationdevice 1114 may be without limitation a switch or a circuit breaker.

An on-ground lock actuator (not shown) may retract on-ground lock (notshown) from latches holding unfixed portion 1128 in the on-groundposition, as shown in FIG. 5. Wing fold system 1100 will then moveunfixed portion 1128 about fold axis 1130 from the on-ground position toflight position 510 as shown in 5. Control module 1112 may control anoutput device from power drive unit 1110 to move wing fold actuator 1102such that it will apply a force to hold unfixed portion 1128 in flightposition 510 until lock 1124 holding unfixed portion 1128 in flightposition 510 may be in engaged position 540 as shown in FIG. 5. Asecondary lock actuator (not shown) may be controlled by control module1112 to engage a secondary lock (not shown) that may provide redundancyto keep unfixed portion 1128 in flight position 510. The secondary lock,and lock 1124 each may be designed to hold unfixed portion 1128 inflight position 510 even if system were to malfunction such that fullpower available from power drive unit 1110 tried to move wing away fromflight position 510 while the secondary lock, and/or lock 1124 may be intheir respective engage position, such as without limitation engageposition 540 as shown in FIG. 5.

With each secondary lock engaged wing fold system 1100 may be considered“locked” in flight position flight position 510, and flight controlscomputer 1118 may command isolation valve isolation device 1114 toisolate control module 1112 from power system 1116. Control panel 1120may then receive status from flight controls computer 1118 and provideindication that unfixed portion 1128 may be in flight position 510.Flight controls computer 1118 and each component of power drive unit1110 may be programmed such that specific timing and/or timing rangelimits are established for each step, and for total time from flightcontrols computer 1118 receiving a command to extend unfixed portion1128 to flight position 510 until unfixed portion 1128 may be locked inflight position 510 and control panel 1120 may indicate unfixed portion1128 as locked in flight position flight position 510.

When a secondary lock and/or a secondary lock actuator may be includedin wing fold system 1100, a secondary power system may power thesecondary lock and/or secondary lock actuator. Without limitation, iflock actuator 1122 may be powered hydraulically, the secondary lockactuator may be powered electrically or pneumatically. Similarly, if andpower drive unit 1110 may contain a hydraulic powered motor, a secondarypower drive may be installed that may be powered without limitationelectrically or pneumatically.

For moving unfixed portion 1128 to the on-ground position after landing,the method described above may be reversed. For landing, flight controlscomputer 1118 may receive a command to move unfixed portion 1128 fromflight position 510 to the on-ground position once the airplane may beon the ground and aircraft speed may be at or below a design speed forwing fold system 1100 hardware. The design speed for wing fold system1100 may be an indicated speed of the aircraft. Aircraft speed inputs toflight controls computer 1118 may inhibit any movement of unfixedportion 1128 above the design speed.

Similarly, unfixed portion 1128 should not move while the aircraft maybe in flight. Hence, sensor inputs to unfixed portion 1128 that theaircraft may be on the ground may inhibit any movement of unfixedportion 1128.

Wing fold system 1100 may then proceed through steps listed below.Control panel 1120 may indicate that unfixed portion 1128 may be “intransit.” Flight controls computer 1118 may command isolation device1114 to open and restore connection of control module 1112 with powersystem 1116. The secondary lock actuator (not shown) may be controlledby control module 1112 to disengage the secondary lock (not shown).After each secondary lock may be disengaged, flight controls computer1118 may command control module 1112 to drive lock actuator 1122 to movelock 1124 to disengaged position 544, and to move unfixed portion 1128from flight position 510 to the on-ground position as shown in FIG. 5.Power drive unit 1110 may move the wingtip about fold axis 1130 fromflight position 510 to the on-ground position as shown in FIG. 5. Whenunfixed portion 1128 reaches the on-ground position, the on-ground lockactuator (not shown) may engage the on-ground lock (not shown) to holdunfixed portion 1128 up in the on-ground position. Similar to lockactuator 1122 and lock 1124, a secondary on-ground lock may be activatedto engage a secondary on-ground lock to provide a redundancy to holdunfixed portion 1128 up in the on-ground position. The secondary foldlock, and the fold lock each may be designed to hold unfixed portion1128 in 514 even if system were to malfunction such that full poweravailable from power drive unit 1110 tried to move wing away from 514while the secondary lock, and/or lock 1124 may be in their respectiveengage position, such as without limitation engage position 540 as shownin FIG. 5.

After all secondary fold locks are engaged flight controls computer 1118may command power system 1116 to isolate control module 1112 from powersystem 1116. Indication may be provided to control panel 1120 and/orelsewhere, that the wing tips are “Folded” in the on-ground position.

Each component shown in FIG. 11 for wing fold system 1100 may also besimilarly present in each wing on the aircraft containing wing foldsystem wing fold system 1100 as shown in FIG. 11. Control panel 1120,flight controls computer 1118, and power system 1116 may provideidentical control to each wing on the aircraft that may contain a powerdrive similar to power drive unit 1110 as described for the illustrativeembodiment shown in accordance with FIG. 11.

The illustration of FIG. 11 is not meant to imply physical orarchitectural limitations to the manner in which different illustrativeembodiments may be implemented. Other item in addition to, in place of,or both in addition to and in place of the ones illustrated may be used.Some components may be unnecessary in some illustrative embodiments.Also, the items are presented to illustrate some functional components.One or more of these blocks may be combined or divided into differentblocks when implemented in different embodiments. For example withoutlimitation, control module 1112 may be combined into flight controlscomputer 1118 or into power drive unit 1110.

Referring now to FIGS. 12A-12D, FIGS. 12A-12D represent across-sectional plan view diagram of a lock for a latch of a wing foldsystem, in accordance with an illustrative embodiment. FIG. 12A is across-sectional plan view diagram of a latch in a closed position with alock in a disengaged position and respective centerlines of fixed lugs,unfixed lug, and a lock, substantially aligned in accordance with anillustrative embodiment. FIG. 12B is a cross-sectional plan view diagramof a lock unable to engage with misaligned lugs of a latch in accordancewith an illustrative embodiment. FIG. 12C is a cross-sectional plan viewdiagram of a lock in a disengaged position when a centerline axis of anunfixed lug may not align with a centerline axis of fixed lugs and acenterline axis of a lock in accordance with an illustrative embodiment.FIG. 12D is a cross-sectional plan view diagram of a lock in an engagedposition in a closed latch in accordance with an illustrativeembodiment.

More specifically, FIGS. 12A-12D depict a cross-sectional plan view oflatch system 1200. Latch system 1200 may include fixed lugs 1204,unfixed lug 1208, lock 1210, lock actuator 1214, stop device 1216, andstop device 1238. Fixed lugs 1204 and unfixed lug 1208 may collectivelyform a portion of latch 1212. Fixed lugs 1204 may be lugs connected tofixed portion fixed portion 1220 of a wing. Unfixed lug 1208 may be alug connected to unfixed portion 1218 of the wing. Without limitation,unfixed portion 1218 and fixed portion 1220 may be illustrative examplesof unfixed portion 1128 and fixed portion 1126 as shown in FIG. 11, andunfixed portion 454 and fixed portion 448 for wing 442 as shown in FIG.4.

Latch system 1200 may be an example in simplified plan form, of aportion of latches 572 and locks 574 in wing fold system 502, as shownin FIG. 5, or a portion of latches 612 and lock 614 as shown in FIG. 6.Latch 1212 may include more unfixed lugs 1204 than the two shown in FIG.12A through FIG. 12D, and more than the one unfixed lug 1208 shown inFIG. 12A through FIG. 12D.

Referring now to FIG. 12A, FIG. 12A is a plan view diagram of a latch ina closed position with a lock in a disengaged position and respectivecenterlines of fixed lugs, unfixed lug, and a lock, substantiallyaligned in accordance with an illustrative embodiment.

More specifically, FIG. 12A shows a condition wherein latch 1212 may bein a closed position, such as shown without limitation by closedposition 530 in FIG. 5, such that centerline axis 1202 of fixed lugs1204 may be substantially aligned with centerline axis 1206 of unfixedlug 1208 and centerline axis 1222 of lock 1210. With latch 1212 closedas shown in FIG. 12A, FIG. 12A may be an illustrative embodiment ofunfixed portion 1218 in flight position, such as without limitationflight position 510 as shown in FIG. 5.

A centerline axis for wing fold actuator 1102 may be fold axis 1130, asshown above in FIG. 11. Fold axis 1130 may not be collocated with lock1210 or may not be in alignment with a centerline axis 1222 of lock1210. As wing fold actuator 1102 rotates unfixed portion 1128 intoflight position 12510 as shown in FIG. 5, lock 1210 may be sized suchthat when centerline axis 1202 of fixed lugs 1204 may be substantiallyaligned with centerline axis 1206 of unfixed lug 1208 that lock 1210 maybe actuated to engage through the center of fixed lugs 1204 and unfixedlug 1208 with a designated clearance between the interior edges ofopenings through fixed lugs 1204 and unfixed lug 1208, or of bushingsthereof, and exterior sides of lock 1210.

The designated clearance between the interior edges of openings throughfixed lugs 1204 and unfixed lug 1208 and may result in substantially nofriction between lock 1210 and the interior edges of openings throughfixed lugs 1204 and unfixed lug 1208, or of bushings thereof. Thus, iffriction forces, between lock 1210 and any lugs of latch 1212, whileinserting lock 1210 into latch 1212 to engaged position, or retractinglock 1210 from latch 1212 to disengaged position are substantially at aminimum level, a force required of lock actuator 1214 for insertion andretraction may be at a minimum level. Without limitation lock actuator1214 may be an example of an embodiment of lock actuator 1122 as shownin FIG. 11, and may be one of the actuators 576 as shown in FIG. 5.

The designated clearance between the interior edges of openings throughfixed lugs 1204 and unfixed lug 1208 and may result in a designatedcontact pressure and/or friction between exterior sides of lock 1210 andthe interior edges of openings through fixed lugs 1204 and unfixed lug1208, or of bushings thereof (bushings not shown to simplify diagram).Control of contact forces during insertion of lock 1210 into latch 1212to a minimum level may reduce wear on lock 1210, fixed lugs 1204,unfixed lug 1208, any bushings associated with any lugs of latch 1212,as well as wear on lock actuator 1214. Thus, if contact forces whileinserting lock 1210 into latch 1212 to engaged position, or retractinglock 1210 from latch 1212 to disengaged position are minimized, a forcerequired of lock actuator 1214 may be minimized.

Accordingly, a size and a weight of lock actuator 1214 may be minimized,and/or a reliability and/or service life of lock actuator 1214 of agiven power may be increased, relative to a condition where centerlineaxis 1202 of fixed lugs 1204 may not substantially aligned withcenterline axis 1206 of unfixed lug 1208. Thereby, a wing containingwing fold system 1100 may be sized such that no component of wing foldsystem 1100 may require a fairing that expands a profile of the wing. Asshown in FIG. 12A, lock 1210 may be in disengaged position 1234 such asdisengaged position 544 is described for FIG. 5.

With lock 1210 engaged between all lugs of latch 1212 contact betweenexterior sides of lock 1210 and the interior edges of openings throughfixed lugs 1204 and unfixed lug 1208 may be sufficient to substantiallyinhibit movement of unfixed portion 1218 of relative to fixed portion1220.

Stop device 1216 may be positioned on fixed portion 1220 such thatunfixed lug 1208 contacts stop device 1216 such that unfixed portion1218 cannot move any further toward a flight position such as flightposition 510 as shown in FIG. 5. Stop device 1216 may be positioned onfixed portion 1220 such that unfixed lug 1208 may contact stop device1216 such that centerline axis 1206 of unfixed lug 1208 alignssubstantially with centerline axis 1202 of fixed lugs 1204 andcenterline axis 1222 of lock 1210. Without limitation, stop device 1216may be a single component as shown in the illustrative embodiment, ormay be a number of components that function together as a systemgenerally located as shown for and performing the functions describedfor stop device 1216.

Unfixed lug 1208 may also include stop device 1238. Stop device 1238 maybe positioned on unfixed lug 1208 such that stop device 1238 may contactstop device 1216 such that centerline axis 1206 of unfixed lug 1208aligns substantially with centerline axis 1202 of fixed lugs 1204 andcenterline axis 1222 of lock 1210. Without limitation, stop device 1238may be a single component as shown in the illustrative embodiment, ormay be a number of components that function together as a systemgenerally located as shown for and performing the functions describedfor stop device 1238.

If unfixed lug 1208 is formed without stop device 1238, then unfixed lug1208 will be sized to include the space indicated by stop device 1238such that unfixed lug 1208 may contact stop device 1216 in the samemanner as depicted in FIGS. 12A, 12C, and 12D for stop device 1238.Thereby, a wing containing wing fold system 1100 may be sized such thatno component of wing fold system 1100 may require a fairing that expandsa profile of the wing.

Similarly, if stop device 1238 is used, but stop device 1216 is notincluded on fixed portion fixed portion 1220, then fixed portion 1220will occupy the space indicated by stop device 1216, and stop device1238 may contact fixed portion 1220 in the same manner it is showncontacting stop device 1216 in FIGS. 12A, 12C, and 12D.

With unfixed portion 1218 in flight position 510, as shown in FIG. 5, ifthe only external force acting on unfixed portion 1218 was gravity, andwing fold actuator 1102 was not restricting movement of unfixed portion1218 about centerline axis 1130 of wing fold actuator 1102, it may bepossible that unfixed portion unfixed portion 1218, acting aboutcenterline axis 1130 of wing fold actuator wing fold actuator 1102, maybe weighted or configured such that unfixed portion 1218 pushes unfixedlug 1208 to rest against stop device 1216 as shown in FIG. 12A.

Alternatively, unfixed portion 1218 may be weighted such that if theonly external force acting on unfixed portion 1218 was gravity, and wingfold actuator 1102 was not restricting movement of unfixed portion 1218about centerline axis 1130 of wing fold actuator 1102, it may bepossible that unfixed portion unfixed portion 1218, acting aboutcenterline axis 1130 of wing fold actuator 1102, may have a restingpoint such that some angle exists between a span of unfixed portion 1128and a span of fixed portion fixed portion 1126. Hence, for unfixedportion 1128 to push unfixed lug 1208 against fixed portion 1126, wingfold actuator 1102 must apply a force on unfixed portion 1128. Referringnow to FIG. 12B. FIG. 12B is a plan view diagram of a lock unable toengage with misaligned latches in accordance with an illustrativeembodiment.

More specifically, FIG. 12B shows a condition where unfixed lug 1208 maynot be in contact with stop device 1216 and centerline axis 1206 ofunfixed lug unfixed lug 1208 may not be aligned with centerline axis1202 of fixed lugs 1204 and centerline axis 1222 of lock 1210.

The illustrative embodiments recognize and take into account that whenan aircraft may be in motion there may be forces acting upon unfixedportion 1218 due to unfixed portion 1218 being connected to an aircraftand reacting to movement of the aircraft. Without limitation the forcesacting upon unfixed portion 1218 may be caused by imperfections or bumpsin the surface the aircraft may be moving over, or due to an operatortechnique during movement of the aircraft. Some of the forces on unfixedportion 1218 may move unfixed lug 1208 into stop device 1216, while someof the forces on unfixed portion 1218 may move unfixed lug unfixed lug1208 away from stop device 1216. If wing fold actuator 1102 cannotrestrict motion of unfixed portion 1218, unfixed lug 1208 may be able tomove to the position shown in FIG. 12B.

Unfixed lug 1208 may be in the position shown by FIG. 12B duringtransition of unfixed portion 1218 between flight position 510 and theon-ground position, as shown without limitation by FIG. 5.Alternatively, for some configurations of unfixed portion 1218, adistribution of weight of components of unfixed portion 1218 may resultin unfixed lug 1208 resting in the position shown by FIG. 12B if unfixedportion 1218 were free to rotate about fold axis 1130 without anyrestriction, and gravity being the only force acting on the mass ofunfixed portion 1218.

When unfixed lug 1208 and fixed lugs 1204 are each positioned as shownin FIG. 12B, if lock actuator 1214 attempts to move lock 1210 through1209 and fixed lugs 1204 of latch 1212 toward engaged position 1232 asshown in FIG. 12D, lock 1210 may be halted by contact with unfixed lug1208. When lock actuator 1214 senses resistance to insertion that may begreater than expected, lock actuator 1214 flight controls computer maydirect lock 1210 to attempt to retract from latch 1212 and return todisengaged position 1234 as shown in FIG. 12A. Thus, if centerline axis1206 of unfixed lug 1208 and centerline axis 1202 of fixed lugs 1204 andcenterline axis 1222 of lock 1210 may be misaligned, without limitationto a degree shown in FIG. 12B or greater, lock 1210 may not be able toextend through latch 1212 to reach engaged position 1232 as shown inFIG. 12D, or as shown in FIG. 5 as engaged position 540 for latch 1212in closed position 530. Latch 1212 may be one of latches 572.

Further, the illustrative embodiments recognize and take intoconsideration that stop device 1216 and/or unfixed lug 1208 may becomeworn or misadjusted such that unfixed lug 1208 may not contact stopdevice 1216 such that centerline axis 1206 of unfixed lug 1208 andcenterline axis 1202 of fixed lugs 1204 and centerline axis 1222 of lock1210 may each be substantially aligned with each other. Accordingly,design adjustments may be desired that allow moving lock 1210 to closedposition 530 when centerline axis 1206 of unfixed lug 1208 does notperfectly align with centerline axis 1202 of fixed lugs 1204 andcenterline axis 1222 of lock 1210.

With reference now to FIG. 12C, FIG. 12C is a cross-sectional plan viewdiagram of a lock in a disengaged position when a centerline axis of anunfixed lug may not align with a centerline axis of fixed lugs and acenterline axis of a lock in accordance with an illustrative embodiment.More specifically, with latch 1212 closed as shown in FIG. 12C, FIG. 12Cmay be an illustrative embodiment of unfixed portion 1218 in a flightposition, such as without limitation flight position 510 as shown inFIG. 5. More specifically, FIG. 12C shows centerline axis 1206 ofunfixed lug 1208 misaligned from centerline axis 1202 of fixed lugs 1204and centerline axis 1222 of lock 1210. As shown, the misalignment of theaxis may not be too large to prevent lock actuator 1214 from insertinglock 1210 through latch 1212 into closed position 530 as shown in FIG.5.

The illustrative embodiments take into account and recognize thatunfixed lug 1208 and/or stop device 1216 may become worn. Thus, latchsensors not shown, which may be an example of latch sensors 566 as shownin FIG. 5, may sense the misalignment of centerline axis 1206 of unfixedlug 1208 away from being substantially aligned with centerline axis 1202of fixed lugs 1204 and centerline axis 1222 of lock 1210. Sensors maysend an alert and/or a request for adjustment. Alert and/or request foradjustment may be sent to a maintenance tracking system and/or to flightcontrols computer 1118 as shown in FIG. 11.

Thus, as can be seen comparing the condition shown in FIG. 12B of theillustrative embodiment to the condition shown in FIG. 12C, there issome amount of angular free play between the span line of unfixedportion 1128 and the span line of fixed portion 1126 that will allowlock 1210 to engage with latch 1212 when latch 1212 is close to, but notfully in, closed position 530 of FIG. 5, as shown in FIG. 12C.

Similarly, with lock 1210 in engaged position 1232, as shown in FIG.12D, angular free play of the span line of unfixed portion 1128 relativeto the span line of fixed portion fixed portion 1126 must be controlledto prevent moments from unfixed portion 1128 acting upon unfixed lug1208 in a manner that applies such a force onto a side of lock 1210 thatthe power of lock actuator 1214 may not be great enough to retract lock1210 from latch 1212.

Therefore, stop device 1216 may be adjustable. Stop device 1216 may bemoved, manually or automatically, or via some combination thereof, sothat when unfixed lug 1208 may be held against stop device 1216 by force1228, that centerline axis 1206 of unfixed lug 1208 may be substantiallyaligned with centerline axis 1202 of fixed lugs 1204 and centerline axis1222 of lock 1210.

Similarly stop device 1238 may be adjustable. Stop device 1238 may bemoved, manually or automatically, or via some combination thereof, sothat when stop device 1238 on unfixed lug 1208 may be held against stopdevice 1216 by force 1228, that centerline axis 1206 of unfixed lug 1208may be substantially aligned with centerline axis 1202 of fixed lugs1204 and centerline axis 1222 of lock 1210. An adjustment to stop device1238 may be made in coordination with or in place of an adjustment tostop device 1216.

Force 1228 may be generated by wing fold actuator 1102 moving unfixedportion 1128, as shown in FIG. 11, toward flight position 510, as shownin FIG. 5, and moving stop device 1238 of unfixed lug 1208 against stopdevice 1216 on fixed portion 1220.

Lock 1210 may have corners 1224, on an end of lock 1210 that may contactunfixed lug 1208, which may be rounded, beveled, or slanted. An openingthrough unfixed lug 1208 may have rounded, beveled, or slanted corners1226 on a side of unfixed lug 1208 that faces lock actuator 1214. Thus,if unfixed lug 1208 is in a position such that lock 1210 moving towardengaged position 1232, as shown in FIG. 5, contacts corners 1224 withcorners 1226 of unfixed lug 1208, then an insertion force from lockactuator 1214 may cause lock 1210 to move unfixed lug 1208 such thatcenterline axis 1206 of unfixed lug 1208 substantially aligns withcenterline axis 1202 of fixed lugs 1204 and centerline axis 1222 of lock1210.

Accordingly, force 1228 holding unfixed lug 1208 against stop device1216 may need to be of a low enough value that force 1230 on lock 1210,provided by lock actuator 1214, may be strong enough to overcome force1228 and move unfixed lug 1208 away from stop device 1216 enough toallow lock 1210 to move through fixed lugs 1204 and unfixed lug 1208 toengaged position 1232 as shown in FIG. 12D.

With reference now to FIG. 12D, FIG. 12D is a cross-sectional plan viewdiagram of a lock in an engaged position in a closed latch in accordancewith an illustrative embodiment. More specifically, engaged position1232 for lock 1210 in latch 1212 may be an example of engaged position1232 as shown in FIG. 5. Lock 1210 may be fully engaged when tangentpoints 1236 of corners 1224 to side of lock 1210 have passed beyond thefar left side of left most fixed lugs 1204.

When lock 1210 may be in engaged position 1232, power system 1116 may beisolated from wing fold actuator 1102 such that force 1228 may be nolonger applied to unfixed lug 1208 and lock 1210 carries any loadskeeping latch 1212 in closed position 530 as shown in FIG. 5. Thus, thedesign provides for maintaining latch 1212 in closed position 530, asshown in FIG. 5, and unfixed portion in 1128 in flight position 510, asshown in FIG. 11 and FIG. 5, via lock 1210 even when no power may besupplied to wing fold actuator wing fold actuator 1102. Accordingly,before flight, power may be removed from lock actuator 1214 to preventunintentional retraction of lock 1210 during flight. Similarly, powermay be removed from wing fold actuator 1102 during flight to inhibitwing fold actuator 1102 from attempting to move unfixed portion 1128away from flight position 510, as shown in FIG. 11 and FIG. 5.

The illustrative embodiments recognize and take into account thatlimiting a size and/or weight of each lock actuator 1214 located in awing may improve performance and/or fuel efficiency of an aircraft.Thereby, a wing containing wing fold system 1100 may be sized such thatno component of wing fold system 1100 may require a fairing that expandsa profile of the wing. Accordingly, it may be desirable for lockactuator 1214 to have the smallest size and weight possible while stillbeing able to produce force 1230 large enough to allow lock 1210 to movethrough fixed lugs 1204 and unfixed lug 1208 to engaged position 1232 asshown in FIG. 12D.

With reference now to FIG. 13, FIG. 13 is a chart indicating momentsabout a wing fold actuator hinge, in accordance with an illustrativeembodiment. More specifically, chart 1300 presents a relative momentabout a centerline of wing fold actuator 1102, such as withoutlimitation fold axis 1130 of unfixed portion 1128, as shown in FIG. 11.Fold axis 1130 may substantially align with a centerline axis of wingfold actuator 1102, as shown in FIG. 11.

Thus, moments about fold axis 1130 may represent moments that wing foldactuator 1102 may need to generate to hold unfixed portion 1128 at theangle indicated by the horizontal axis of chart 1300. In other words, arelative torque value on an output device of wing fold actuator 1102 maybe equivalent to a momentum shown for various angles between a span lineof unfixed portion 1128 and a span line of fixed portion 1126 for a wingcontaining wing fold actuator 1102, measured from the span line of fixedportion 1126 rotating upward toward the aircraft body. The span line ofunfixed portion 1128 may be represented by a line extending from unfixedportion 1128 toward fixed portion 1126 along a top surface of sparextending from unfixed portion 1128 that associates with a spar of fixedportion 1126. The span line of fixed portion fixed portion 1126 may berepresented by a line extending from fixed portion 1126 toward unfixedportion 1128 along a top surface of a spar extending from fixed portion1126 that associates with unfixed portion 1128.

The vertical axis of chart 1300 represents relative values for momentsabout fold axis 1130. A positive value may be assigned to a moment thatacts in a direction that moves unfixed portion 1128 toward the on-groundposition, as shown in FIG. 5. Similarly, torque at an output device fromwing fold actuator 1102 may be positive if it moves unfixed portion 1128toward the on-ground position. A negative value may be assigned to amoment that acts in a direction the moves unfixed portion 1128 towardflight position 510, as shown in FIG. 5. Similarly, torque at the outputdevice from wing fold actuator 1102 may be negative if it moves unfixedportion 1128 toward flight position 510.

At the horizontal axis, the moment about fold axis 1130 has a value ofzero. Although specific magnitudes are not presented along the verticalaxis, the scale may be considered as a linear one, such that a firstpoint along the vertical axis that lies twice the distance from thehorizontal axis as a second point may be considered to represent amoment of twice the magnitude as the second point.

The horizontal axis of chart 1300 represents a value for the anglebetween the span line of fixed portion 1126 and the span line of unfixedportion 1128. At the vertical axis a zero degree angle may exist betweenthe span line of fixed portion 1126 and the span line of unfixed portion1128 of the wing containing wing fold actuator 1102.

Line 1302 presents a relative indication of the torque required from anoutput device of wing fold actuator 1102 to position unfixed portion1128 as it moves between the on-ground position and flight position 510,as shown in FIG. 5, when the only force acting on unfixed portion 1128may be the weight of unfixed portion 1128. In other words, line 1302presents a relative indication of the torque required from an outputdevice of wing fold actuator 1102 to position unfixed portion 1128 as itmoves between the on-ground position and flight position 510, as shownin FIG. 5, for a static aircraft without wind on a level surface. Noinfluences of wind, ground slope, or movement of the aircraft arerepresented in line 1302.

Without limitation, the on-ground position for unfixed portion 1128 maybe a position near the 80 degree mark on the horizontal axis of chart1300. Without limitation, flight position 510 may be a position near the0 degree mark, or vertical axis, on the horizontal axis of chart 1300.FIG. 13 is not intended to limit possible angles between the span lineof fixed portion 1126 and the span line of unfixed portion unfixedportion 1128. In some embodiments, the on-ground position may extendbeyond 90 degrees. In some embodiments, flight position 510 may be somenegative angle less than zero.

As can be seen in FIG. 13, a zero moment may exist when the angle may besome value greater than zero. Thus, due to the weight of components ofunfixed portion 1128, if unfixed portion 1128 were allowed to freelyrotate about fold axis 1130, as shown in FIG. 11, then unfixed portion1128 would rest displaced from flight position 510 some number ofdegrees toward the on-ground position, as shown in FIG. 5.

Thus for unfixed lug 1208 to be aligned with fixed lugs 1204 and latch1212 to be in closed position 530 so that lock 1210 may extend toengaged position 1232, as shown in FIG. 5, then wing fold actuator 1102must provide some negative moment so that angle between the span ofunfixed portion 1128 and fixed portion 1126 will be held at an angledesignated for flight position 510. The angle designated for flightposition 510 may be zero, or may be some other angle that may be greaterthan or less than zero when an anhedral wing tip configuration may bedesired.

The illustrative embodiments recognize and take into account that theweight of unfixed portion 1128 may not be the only force acting uponunfixed portion 1128 and wing fold actuator 1102. Wind may blow from anydirection relative to 1128 and at various magnitudes. Withoutlimitation, when unfixed portion 1128 on a left wing of an aircraft maybe moving from the on-ground position toward flight position 510, a windfrom the left side of the aircraft would act against a bottom surface ofunfixed portion 1128 and push it towards the on-ground position, thusadding a positive moment component about fold axis 1130, and requiringwing fold actuator 1102 to produce a greater negative moment to overcomethe positive moment added by the wind and keep unfixed portion 1128moving toward the on-ground position. A wind from the right side of theaircraft would have the opposite effect. Higher magnitude winds or windsgusting to higher magnitudes may increase the value of the resultingmoments. Thus, lines 1304 represent that, due to winds, some range ofvalues may be added to or subtracted from the moment values for a staticaircraft without wind represented by line 1302.

The illustrative embodiments recognize and take into account that forcesother than wind may affect loads on unfixed portion 1128. Withoutlimitation, aircraft movement on the ground may generate lift and dragforces as air passes across unfixed portion 1128. The lift and dragforces may depend upon the angle between a chord line of unfixed portion1128 and a relative wind to unfixed portion 1128. The relative wind maybe dependent upon environmental conditions, and upon an indicated speedof the aircraft containing unfixed portion 1128.

Thus, the range represented by lines 1304 may be limited by somespecified maximum indicated airspeed limit for allowing movement ofunfixed portion unfixed portion unfixed portion 1128 to be commanded bywing fold system 1100. Hence, lines 1304 may represent a range limitedby a design speed for wing fold system 1100 operation that may take intoaccount and recognize some specified maximum indicated airspeed limitfor allowing movement of unfixed portion unfixed portion unfixed portion1128 to be commanded by wing fold system 1100.

Further, aircraft vibrations during movement, flex in components ofunfixed portion 1128 and/or fixed portion 1126, and affects from unevenpavement and/or operator technique may cause variations in positive andnegative moments about fold axis 1130 for unfixed portion 1128. Withoutlimitation, a force generated during turning of the aircraft, and/or dueto asymmetrical engine thrust or wheel break forces, and/or due toflight control deflections, and/or a slope or a bank of the ground theaircraft may be on may also affect a positive and/or a negative momentabout fold axis 1130.

Thus, lines 1306 indicate that some relative increase or decrease inmoments about fold axis 1130, and thus torque required from outputdevice of wing fold actuator 1102 may result from forces other than onlya weight of unfixed portion 1128 and wind acting on unfixed portion1128. Lines 1306 recognize and take into account that vibration effectsfrom other components in an aircraft containing wing fold system 1100and/or forces resulting from bumps or unevenness in a surface theaircraft moves upon, and/or forces generated by possible impact ofunfixed portion 1128 and/or the aircraft with objects above the surfacethe aircraft moves upon, may be affected by an indicated airspeed of theaircraft.

Thus, the range represented by lines 1306 may be limited by somespecified maximum indicated airspeed limit for allowing movement ofunfixed portion unfixed portion unfixed portion 1128 to be commanded bywing fold system 1100. Hence, lines 1306 may represent a range limitedby a design speed for wing fold system 1100 operation that may take intoaccount and recognize some specified maximum indicated airspeed limitfor allowing movement of unfixed portion unfixed portion unfixed portion1128 to be commanded by wing fold system 1100.

Although in the example shown in chart 1300, the range of magnitude ofvariations for lines 1306 are greater than those for lines 1304, theopposite may be the case. Regardless of the specific values of thecontributing forces, a sum of all forces acting upon unfixed portion1128 may produce a total moment about fold axis 1130 that may vary bysome magnitude above and/or below a moment about fold axis 1130 due onlyto the weight of unfixed portion 1128 as shown by line 1302.

Thus, wing fold actuator 1102 may be required to have enough power toprovide torque to an output device, which may rotate unfixed portion1128, that may be at least equal to the total moment about fold axis1130 due to a sum of all forces acting upon unfixed portion 1128. Hence,for the example of chart 1300, an output device of wing fold actuator1102 may be required to provide positive torque equal to at least thetotal positive maximum 1312 moment shown on chart 1300, and torque equalto at least the total negative maximum moment shown on chart 1300.Accordingly, for wing fold actuator 1102 to provide the total positivemaximum 1312 moment, power drive unit 1110 must be able to supply enoughpower to wing fold actuator 1102 such that wing fold actuator 1102 maygenerate a maximum force that will produce positive torque equal to atleast the total positive maximum value 1312. Further, reliabilityrequirements, or regulatory requirements may increase the requiredtorque capability, by some multiple, for wing fold actuator 1102.Without limitation reliability may include accurately performing withinspecifications or be related to minimizing a failure rate. Additionally,wing fold actuator 1102 may be required to provide positive torque equalto at least the total positive maximum after the aircraft hasexperienced, without limitation, some specified acceleration loadfactor, and or be able to perform without degradation after some numberof hours of operation at some vibration rate and/or range. Wing foldactuator 1102 may be required to provide positive torque equal to atleast the total positive maximum after the aircraft has experienced,without limitation, some specified range or change in ambienttemperature, and/or pressure, and/or humidity, and/or electrical currentsurge. Without limitation, such requirements may include FederalAviation Administration aircraft certification requirements, such aswithout limitation 14 Code of Federal Regulations (CFR) Part 21, and/orairworthiness requirements, such as without limitation 14 CFR Part 25.Regulations may require capability to operate wing fold actuator 1102and wing fold system 1100, as shown in FIG. 11, after an aircraft mayexperience acceleration loads that may be from minus 4 to plus 200 timesthe force of gravity.

Typically, a wing fold actuator may be manufactured to produce a samemaximum value of negative torque to an output device as the maximumvalue of positive torque produced by the wing fold actuator to an outputdevice. Hence, it can be seen that if wing fold actuator 1102 hassufficient power to meet the total positive maximum indicated in chart1300, then it may be capable of providing an output device with morethan twice the total negative maximum torque required.

The illustrative embodiments recognize and take into account thatoperating wing fold actuator 1102 at maximum output every time wing foldactuator 1102 may be operated may reduce a reliability and/or a meantime to replacement for wing fold actuator 1102. Regulating wing foldactuator 1102 output, to a level only required to overcome the actualmoments acting upon unfixed portion 1128 about fold axis 1130 may reducestress and/or wear on wing fold actuator 1102, and/or componentsassociated with wing fold actuator 1102. Regulating wing fold actuator1102 output, to a level only required to overcome the actual momentsacting upon unfixed portion 1128 about fold axis 1130 may increase thereliability and/or mean time to replacement for wing fold actuator 1102.

As discussed above for FIG. 12A through FIG. 12D, lock 1210 may beextended by lock actuator 1214 through latch 1212 into engaged position1232 as shown in FIG. 12D, and may be retracted from latch 1212 todisengaged position 1234 when latch 1212 may be in closed position 530,as shown in FIG. 5 and above in FIGS. 12A, 12C, and 12D. Latch 1212 maybe in closed position 530 when unfixed portion 1128 may be in flightposition 510, as shown in FIG. 5 and above in FIGS. 12A, 12C, and 12D.As shown for the illustrative embodiment of FIG. 13, unfixed portion1128 may be extended to flight position 510 when an angle between a spanof unfixed portion 1128 and a span of fixed portion 1126 may be at ornear zero degrees. A span of fixed portion 1126 may be known as a wingreference plane. The wing reference plane may be some number of degreesseparate from a line formed along the surface of the ground beneath wingfold system 1100.

Chart 1300 shows that when lock 1210 may need to extend into or retractfrom latch 1212, and the angle between the span of unfixed portion 1128and the span of fixed portion 1126 may be at or near zero degrees, thatthe torque needed from wing fold actuator 1102 to hold unfixed portion1128 in the proper position may need to be equal only to the values inlock range 1310. As shown by chart 1300, the moments within lock range1310 are significantly less than maximum value 1312. Maximum value 1312represents the total positive maximum moment needed to hold unfixedportion 1218 in the on-ground position, as shown in FIG. 5 or in FIG. 2.

In the illustrative embodiment represented by chart 1300, the on-groundposition for unfixed portion 1128 may be represented by an angle betweenthe span of unfixed portion 1128 and the span of fixed portion 1126 thatmay be greater than 80 degrees. In potential operating conditions forwing fold system 1100, maximum value 1312 may be at least 7 timesgreater than the value of negative maximum indicated for line 1302.

Thus, flight controls computer 1118 may direct control module 1112 toregulate an output device of wing fold actuator 1102 to push stop device1238 of unfixed lug 1208 into stop device 1216 of fixed portion 1220 andhold both stop devices in a position shown by FIG. 12A, using a forcethat may be no larger than required to generate a moment having a valueat the greater limit of lock range 1310 represented by lines 1308,instead of some greater value outside of lock range 1310. Hence, inoperation, as compared to a common wing fold actuator that outputs aforce to produce a moment having a value that may be at least as greatas maximum value 1312, the force output required from wing fold actuator1102 may be regulated down to a value within lock range 1310. Thus, byreducing an output required from wing fold actuator 1102 duringoperations extending lock 1210 into engaged position 1232, shown in FIG.12D, and retracting lock 1210 into disengaged position 1234, shown inFIG. 12A, at least one of a reliability, and a mean time to replacementfor wing fold actuator 1102, may be increased, and/or a size and weightof wing fold actuator 1102 may be reduced, as compared to a common wingfold actuator that outputs a force to produce a moment having a valuethat may be at least as great as maximum value 1312. Thereby, a wingcontaining wing fold system 1100 may be sized such that no component ofwing fold system 1100 may require a fairing that expands a profile ofthe wing.

Further, by wing fold actuator 1102 holding centerline axis 1206 ofunfixed lug 1208 in the alignment with centerline axis 1202 andcenterline axis 1222 as shown in FIG. 12A, forces required of lockactuator 1214 for transitioning lock 1210 in or out of latch 1212 may beheld to a minimum value. Thus, by reducing an output required from lockactuator 1214 to a minimum during operations extending lock 1210 intoengaged position 1232, shown in FIG. 12D, and retracting lock 1210 intodisengaged position 1234, shown in FIG. 12A, at least one of areliability, and a mean time to replacement for lock actuator 1214 maybe increased, and/or a size and weight of lock actuator 1214 may bereduced, as compared to a common lock actuator 1214 that may not operatewith wing fold actuator 1102 holding centerline axis 1206 of unfixed lug1208 in the alignment with centerline axis 1202 and centerline axis 1222as shown in FIG. 12A. Thereby, a wing containing wing fold system 1100may be sized such that no component of wing fold system 1100 may requirea fairing that expands a profile of the wing.

Accordingly, it may be desirable to have a method and apparatus that mayallow wing fold actuator 1102 to limit force supplied by an outputdevice of wing fold actuator 1102 to only values that are within therange indicated by lock range 1310. Wing fold actuator 1102 may be ageared rotary actuator. Force supplied by wing fold actuator 1102 maygenerate torque on an output device. Thus, when moving lock 1210 betweendisengaged position disengaged position 1234 to engaged position engagedposition 1232, as shown in FIGS. 12A and 12D respectively, torquerequired from an output device of wing fold actuator 1102 may be reducedby a factor of 7 times or more

More advantageously, it may be desirable to have a method and apparatusthat may allow wing fold actuator 1102 to limit torque supplied by anoutput device of wing fold actuator 1102 to only a value that equals theactual moment about fold axis 1130 in real time as wing fold actuator1102 may be at any given angle represented in FIG. 13. In other words,output force and work produced by wing fold actuator 1102 may beminimized when force supplied by wing fold actuator 1102 may beregulated by flight controls computer 1118 and control module 1112 tothe actual moment acting about fold axis 1130 on wing fold actuator 1102in real-time at any given angle for wing fold actuator 1102 throughoutthe range from the on-ground position to flight position 510, as shownin FIG. 5.

When moving lock 1210 between disengaged position 1234 to engagedposition 1232, as shown in FIGS. 12A and 12D respectively, force and/ortorque required from an output device of wing fold actuator 1102 thatmay produce a force able to control moments about fold axis 1130 with avalue within lock range 1310 may be 7 times or more smaller as comparedto a common wing fold actuator that constantly produces a force and/ortorque required to control moments about fold axis 1130 at maximum value1312.

Thus, referring now back to FIG. 11, flight controls computer 1118 mayreceive inputs from sensors, which may include without limitationsensors 564, that allow flight controls computer 1118 to compute theactual moment about fold axis 1130 and regulate torque provided by anoutput device of wing fold actuator wing fold actuator 1102 to moveunfixed portion 1128 at a desired rate, or to hold unfixed portion 1128in a desired position. Sensors, which may include without limitationsensors 564, may provide indications for a position and a status of eachcomponent of wing fold system 1100, and of an environment conditionaffecting the aircraft containing wing fold system 1100, such thatflight control computers may compute in real-time the actual momentabout fold axis 1130 due to all factors, including without limitationwind, aircraft movement, weight and balance of wing fold actuator 1102about fold axis 1130, and lift and/or drag on unfixed portion 1128and/or fixed portion fixed portion 1126.

Status 402 and/or warning system 426 and/or status 504, and/or aircraftsystem status 590 and/or sensors 564 may also include wing fold system502 recognizing a sensor status. The sensor status may be a status foreach sensor such that a fault and/or failure in each sensor may berecognized by flight controls computer 1118 and an indication of asensor status may be provided to control panel control panel 1120 and/orother associated systems.

Further, status 402 and/or warning system 426 and/or status 504, and/oraircraft system status 590 and/or sensors 564 may include sensorsrecognizing a status of flight controls computer 1118 and/or componentsthereof. Thus, an input data failure and/or a fault and/or a failure ofa hardware component and/or software function of flight controlscomputer 1118 may be recognized and an indication for a flight controlscomputer 1118 status may be provided to control panel 1120 and/or otherassociated systems.

Further still, status and/or a fault and/or a failure in a component ofcontrol panel 1120 may also be recognized and may be provided to controlpanel 1120 and/or other associated systems. Thus, a position and/orstatus of a wing tip control device and any fault or failure of thedevice may be recognized and/or may be indicated at control panel 1120and/or other associated systems.

For any given operation transitioning unfixed portion 1128 betweenflight position 510 and the on-ground position, the actual momentsacting about fold axis 1130 will be represented by a single continuousline whose points fall between the ranges represented by lines 1308. Aminimum output required of wing fold actuator 1102 may occur when outputforces from wing fold actuator 1102 moving unfixed portion 1128 aresufficient to generate moments equal to move unfixed portion 1128through the angles represented by the single continuous line at a desirerate.

Flight controls computer 1118 may thus direct control module 1112 toregulate power supplied to wing fold actuator 1102, to produce a forcebased upon the actual moment acting on fold axis 1130, that may moveunfixed portion 1128 at a desired rate in a desired direction, or holdunfixed portion 1128 in a desired position. Thus, as compared to acontrol module that provides power based on some assumed potential rangeof required values, as may be represented without limitation by lines1308 in FIG. 13, control module 1112, directed by flight controlscomputer 1118, may allow wing fold actuator 1102 to move unfixed portion1128 with significantly less torque. Thus, control module 1112, directedby flight controls computer 1118 may continuously decrease the work loadof wing fold actuator 1102, as compared to a control module thatprovides power based on some assumed potential range of required values.

Hence, the method as described for FIG. 7A above may also include step710 modified to include the transition of the wing tip to be based upondynamic load control of the actuator of the wing fold system. Thereby,flight controls computer 1118 may limit output of power drive unit 1110such that only the force required to move wing fold actuator 1102 to aspecified position at a rate specified will be dynamically provided inreal time based upon actual loads acting on components of wing foldsystem 1100.

Thus, in an illustrative example if a moment a acting about fold axis1130 for 1130 unfixed portion 1128 during lock engagement may be a valueindicated by the point where line 1302 intersects the vertical axis, andcontrol module 1112 regulates the power to wing fold actuator 1102 toprovide an output that matches that value, then the output produced bywing fold actuator 1102 may be reduced by a factor of 7 times or more ascompared to a common wing fold actuator that constantly produces a forceto match the value of moments at maximum value 1312. Without limitation,if the flight controls computer 1118 computes a moment value, based oninputs from without limitation sensors 564, that may be outside a rangeof predicted values, control module 1112 may limit torque provided bypower drive unit 1110 to a limit within the predicted range. Thislimiting produced torque to a value below a computed would also cause anannunciation to maintenance personnel to possibly perform an inspectionor further maintenance.

Further, flight controls computer may track and record withoutlimitation all data related to the computed moments about fold axis1130, and of all power levels supplied to wing fold actuator 1102.Hence, plots of single continuous lines for actual transition of unfixedportion 1128 between flight position 510 and the on-ground position maybe created. Thus, an operating history may be created from the data thatprovides information without limitation about loads and stresses on eachcomponent of wing fold system 1100. Without limitation, cumulative dataand/or trends from the recorded information from sensors and/or computedmoments about fold axis 1130 may be used to improve maintenancediagnostics and or direct appropriate mean time between replacement ofwing fold actuator 1102 and/or other components of wing fold system1100.

Referring now to FIG. 14A and FIG. 14B: FIG. 14A is a diagram for ahydraulic control system for a wing fold system with a motor driven byvariable differential hydraulic power, in accordance with anillustrative embodiment; FIG. 14B is a diagram for a hydraulic controlsystem for a wing fold system with a motor driven by fixed differentialhydraulic power, in accordance with an illustrative embodiment. Asmentioned above for FIG. 11, power system 1116 may be without limitationan electric, a pneumatic, or a hydraulic system. FIG. 14A and FIG. 14Bmay depict examples of hydraulic power system 1400 for wing fold system1100, in accordance with an illustrative embodiment.

Hydraulic power system 1400 may include aircraft hydraulic system 1402,isolation valve 1404, hydraulic control module 1406, power drive unit1408, wing fold actuator 1410, lock actuator 1412, flight controlscomputer 1414, and control panel 1416.

Aircraft hydraulic system 1402, isolation valve 1404, hydraulic controlmodule 1406, power drive unit 1408, wing fold actuator 1410, lockactuator 1412, flight controls computer 1414, and control panel 1416 maybe without limitation examples of power system 1116, isolation device1114, control module 1112, power drive unit 1110, wing fold actuator1102, lock actuator 1122, flight controls computer 1118, and controlpanel 1120, respectively as presented in FIG. 11, in accordance with anillustrative embodiment. Although FIG. 14A and FIG. 14B shows only onewing, aircraft hydraulic power system 1402 and flight controls computer1414 may be connected to and control a wing fold system in another wing,as indicated by block 1438. The other wing may contain all the featuresshown in and discussed for hydraulic pressure system 1400 of FIG. 14Aand FIG. 14B.

In an illustrative embodiment, hydraulic power system 1400 may power andcontrol wing fold system 1100. Referring now to FIG. 14A, hydraulicfluid and pressurization from aircraft hydraulic power system 1402 maybe connected to provide hydraulic fluid and pressure to hydraulic powersystem 1400. Aircraft hydraulic power system 1402 may be an example ofpower system 1116 as shown in FIG. 11, in accordance with anillustrative embodiment.

Isolation valve 1404 may isolate all hydraulic fluid and pressure fromhydraulic power system 1400. Isolation valve 1404 may be an example ofisolation device 1114 as shown in FIG. 11, in accordance with anillustrative embodiment. Isolation of all hydraulic fluid and pressurefrom hydraulic power system 1400 may prevent inadvertent movement oflock 1412. Lock 1412 may be an example of lock 1124 as shown in FIG. 11or lock 1210 as in FIG. 12A through FIG. 12D. Thus, redundancy may beprovided that may prevent undesired disengagement of lock 1412 fromlatch 1212 when unfixed portion unfixed portion 1128, as shown in FIG.11, is desired to be flight position 510, as shown in FIG. 5 and FIG. 1.

Redundancy may also be provided by isolation of all hydraulic fluid andpressure from hydraulic power system 1400 that may prevent activation ofwing fold actuator 1410 when movement of unfixed portion 1128 may beundesired. When isolation valve 1404 may be open, hydraulic fluid andpressure from aircraft hydraulic power system 1402 flow into hydrauliccontrol module 1406.

Hydraulic control module 1406 may be an example of control module 1112as shown in FIG. 11, in accordance with an illustrative embodiment.Hydraulic control module 1406 may have direction valve 1418 that maycontrol hydraulic fluid and pressure from hydraulic control module 1406to lock actuator 1412 to activate a lock, such as lock 1210 as shown inFIG. 12A through FIG. 12D, in an extend or a retract direction. Lockactuator 1412 may be an example of lock actuator 1214 in accordance withan illustrative embodiment.

Hydraulic control module 1406 may have valve 1420 to regulate hydraulicfluid and pressure sent to power drive unit 1408. Power drive unit 1408may be an example of power drive unit 1110 as shown in FIG. 11, inaccordance with an illustrative embodiment. Power drive unit 1408 mayconvert hydraulic power to a force that drives wing fold actuator 1410.Wing fold actuator 1410 may be an example of wing fold actuator 1102 asshown in FIG. 11, in accordance with an illustrative embodiment.

Power drive unit 1408 may include brake 1430 and motor 1434. Brake 1430may be a device that prevents motor 1434 from moving. Brake 1430 may bedesigned such that when aircraft hydraulic power system 1402 may beremoved from hydraulic control module 1406, that brake 1430 will act toprevent any movement of motor 1434 and thus prevent any movement of wingfold actuator 1410 and/or fixed portion unfixed portion 1218. Brake 1430may be preloaded to hold motor 1434 motionless. Without limitation, apreload on brake 1430 to hold motor 1434 motionless may be provided by aspring configuration. When hydraulic pressure may be present inhydraulic control module 1406, disengage valve disengage valve 1432 mayopen to allow hydraulic pressure to overcome spring pressure preventingmotor 1434 from moving.

Thus, if aircraft hydraulic power system 1402 will to lose all pressure,then brake 1430 would be applied to motor 1434. Without limitation,brake 1430 could be a clamp type configuration, or a lock pin typeconfiguration, or any configuration that may be set to stop movement ofmotor 1434 and wing fold actuator 1410 when aircraft hydraulic powersystem 1402 fails to provide hydraulic pressure to hydraulic controlmodule 1406.

A brake in power drive unit 1110 may function analogously to brake 1430when power system 1116 may be other than hydraulically powered. Withoutlimitation, if power system 1116 may be electric, an electrical chargemay flow through control module 1112 to disengage a brake in power driveunit 1110 from engaging a motor in power drive unit 1110. If electricalpower from power system 1116 were to fail, then the charge being removedfrom the brake in power drive unit 1110 would result in a preloadedforce on the brake applying the brake to prevent any motion of the motorin power drive unit 1110.

When unfixed portion 1128 moves in a rotational manner, wing foldactuator 1410 may be a geared rotary actuator. When wing fold actuator1410 may be a geared rotary actuator, the force produced by power driveunit 1408 may be a torque. Torque may be transferred from power driveunit 1408 to wing fold actuator 1410 via a linkage such as withoutlimitation torque tube 1108, angle gearbox 1106, and torque tube 1104being connected to wing fold actuator wing fold actuator 1102 as shownwithout limitation in FIG. 11, in accordance with an illustrativeembodiment.

Without limitation, valve 1420 may be an electrohydraulic servo valve.When valve 1420 may be an electrohydraulic servo valve, a hydraulic line1422 may connect to and drive motor 1434 in power drive unit 1408 in adirection that will move unfixed portion 1128 toward flight positionflight position 510, as shown in FIG. 5, and a hydraulic line 1424 mayconnect to and drive motor 1434 in power drive unit 1408 in an directionthat will move unfixed portion 1128 toward on-ground position. Pressuresensors 1436 may detect a pressure in each respective line and reporteach respective pressure to flight controls computer 1414 via remoteelectronics unit 1426.

Flight controls computer 1414 may monitor pressures in hydraulic line1422 and hydraulic line 1424 and calculate a pressure differentialbetween hydraulic line 1422 and hydraulic line 1424. Valve 1420 may alsohave a sensor that informs flight controls computer 1414 of a positionof valve 1420. Thus, combined with feedback from sensors providing,without limitation a position and a status of wing fold actuator 1410and unfixed portion 1128 as well as other components of wing fold system1100, flight controls computer 1414 may direct hydraulic control module1406 to position valve 1420 to produce a specified output from powerdrive unit 1408 that will provide a desired force from wing foldactuator 1410 to generate the desired moment about fold axis 1130, asshown in FIG. 11, needed to move unfixed portion 1128 to a specifiedposition at a specified rate.

Valve 1420 may have an associated valve position sensor 1428. Valveposition sensor 1428 may send position of valve 1420 back to flightcontrols computer 1414. Valve position sensor 1428 may send position ofvalve 1420 back to flight controls computer 1414 via remote electronicsunit 1426. Remote electronics unit 1426 may be an example ofanalog-digital converter unit 1132, as shown in FIG. 11.

In operation, hydraulic control module 1406 controlling a pressuredifferential between hydraulic line 1422 and hydraulic line 1424 maycontrol a direction of motion and torque at an output device for orpower drive unit 1408 that drives wing fold actuator 1410 and movesunfixed portion 1128. Hence, inputs to flight controls computer 1414 of,without limitation status 402 and/or status 504 and/or from sensors 564,as shown in FIG. 4 and/or FIG. 5, as well as sensors providing input toflight controls computer 1414 for acceleration forces due to gravity onunfixed portion 1128 and/or fixed portion 1126, and/or componentsthereof, may be used by flight controls computer 1414 to compute, inreal time, the actual moments acting about fold axis 1130 due to allforces acting upon unfixed portion 1128 and fixed portion 1126.Acceleration forces due to gravity on unfixed portion 1128 and/or fixedportion 1126, and/or components thereof may change without limitation asthe aircraft containing wing fold system 1100 may roll over a bump on asurface at an airport.

Flight controls computer 1414 may send a command to hydraulic controlmodule 1406 to adjust valve 1420 such that power drive unit 1408 willsupply the least torque required to drive wing fold actuator 1410 andunfixed portion 1128 at a rate and to a position specified. Thespecified position may be determined in flight controls computer 1414 bya command received in flight controls computer 1414 from control panel1416.

In some embodiments, motor 1434 may be a variable displacement motor.When motor 1434 may be a variable displacement motor, only one ofhydraulic line 1422 or hydraulic line 1424 may be needed to regulatepressure and hydraulic fluid flow direction delivered to motor 1434 inpower drive unit 1408 from hydraulic control module 1406. When motor1434 may be a variable displacement motor, valve 1420 may be adirectional control valve. Flight controls computer 1414 may controlvalve 1420 in hydraulic control module 1406 such that a variabledisplacement motor as motor 1434 in power drive unit 1408 may receivehydraulic fluid and pressure from a single hydraulic line and vary thetorque and speed of movement of wing fold actuator 1410.

When power system 1116 may be electrical instead of hydraulic, valve1420 may be replaced by an electrical component that may vary anelectrical current delivered to power drive unit 1110. The electricalcomponent may be without limitation a potentiometer and/or a variableresistor. When power system 1116 may be electrical instead of hydraulic,power system 1116 may include an electrically driven motor.

Remote electronics unit 1426 may convert analog signals to digitalsignals and/or digital signals to analog signals. Remote electronicsunit 1426 may without limitation allow transmission of signals and/orinformation between hydraulic control module 1406, and componentscommunicating therewith, and flight controls computer 1414 via wirelesstransmissions and/or transmission via some number of wires, wherein thenumber may be one.

Thus, by reducing a number of wire bundles needed to transmitinformation and commands between flight controls computer 1414 andhydraulic control module 1406 and/or components communicating withhydraulic control module 1406, as compared to a system not using 1426, aweight of and/or a space occupied by the number of wire bundles may beeliminated. Eliminating the weight of and/or the space occupied by acomponent of hydraulic power system 1400 may allow a reduction in aprofile of a size of a wing containing hydraulic power system 1400and/or reduce a total weight of the wing. A reduction in a profile of asize of a wing containing hydraulic power system 1400 and/or reduce aweight of the wing may result in improved performance and/or fuelefficiency for an aircraft containing hydraulic power system hydraulicpower system 1400. Thereby, a wing containing wing fold system 1100 maybe sized such that no component of wing fold system 1100 may require afairing that expands a profile of the wing.

Further, hydraulic power system 1400 may have manual reversioncapability, such that lock 1412 may be retracted manually, and anexternal power drive, which may be without limitation a hand toolconnecting to power drive unit 1408 and/or wing fold actuator 1410and/or some linkage connected thereto.

Referring now to FIG. 14B, FIG. 14B is a diagram for a hydraulic controlsystem for a wing fold system with a motor driven by fixed differentialhydraulic power, in accordance with an illustrative embodiment. Theillustrative embodiment of FIG. 14B takes into account and recognizesthat latches, such as without limitation latch 1212 may be held inclosed position, as shown in FIG. 12A so that lock 1210 may be movedinto and out of engaged position 1232 as shown in FIG. 12D with aminimum of stress and wear on latch 1212 and lock 1210 and lock actuator1214 components when unfixed lug 1208 may be held by force 1228 againstfixed portion 1220. The illustrative embodiment of FIG. 14B takes intoaccount and recognizes that a reliability and mean time to replacementfor motor 1434 may be increased if the output from and/or work done bymotor 1434 may be kept to a reduced level compared to motor 1434 alwaysproviding an output that supplies force to wing fold actuator 1410 suchthat wing fold actuator 1410 may always supply enough force to generatemaximum value 1312 moment about fold axis 1130, as shown in FIG. 11 andFIG. 13.

Hence, when motor 1434 drives wing fold actuator 1410 in a direction tomove unfixed portion 1128 toward flight position flight position 510,without limitation as also shown in FIG. 12D, the force to generatemaximum value 1312 moment about fold axis fold axis 1130 may not beneeded. A lower force will suffice, so long as it may be great enough toovercome the moments in lock range 1310 as shown in FIG. 13.

Thus, even when valve 1420 may not be an electrohydraulic servo valve,or motor 1434 may not be a variable displacement motor, or flightcontrols computer 1414 may not compute an actual moment for unfixedportion 1128 about fold axis 1130 in real time and dynamically regulateoutput from power drive unit 1408 to adjust for the actual moment suchthat unfixed portion 1128 may be moved at a specified rate to aspecified position, it may be still possible to provide the advantagesof operating motor 1434 to move unfixed portion 1128 to flight position510 without powering motor 1434 to produce a force required to match amoment about fold axis 1130 equal to maximum value 1312.

As shown by FIG. 14B, pressure regulating valve pressure regulatingvalve 1440 may be connected to hydraulic line 1422 that powers motor1434 in power drive unit 1408 in the direction to move unfixed portion1128 toward flight position 510. Hence, a pressure differential may beprovided between hydraulic line 1422 and hydraulic line 1424 by reducingpressure in hydraulic line 1422 via pressure regulating valve 1440. Avalue for a pressure remaining in hydraulic line 1422 as a result ofopening pressure regulating valve 1440 may be a value that may besufficient to provide enough force to wing fold actuator 1410 to equalmaximum moments predicted for lock range 1310. Maximum moments predictedfor lock range 1310 may depend upon the design speed of the aircraftwhile operating hydraulic pressure system 1400 and other design factorssuch as without limitation maximum winds that may be present whileoperating hydraulic power system 1400. Without limitation, if aircrafthydraulic power system 1402 supplied hydraulic fluid pressurized at 3000pounds per square inch to hydraulic control module 1406, while apressure in hydraulic line 1424 may be at 3000 pounds per square inch,pressure regulating valve 1440 may reduce a pressure in hydraulic line1422 down to 1000 pounds per square inch. Opening of pressure regulatingvalve 1440 to reduce the pressure in hydraulic line 1422 may becommanded from flight controls computer 1414 based upon a sensedposition of unfixed portion 1128. Without limitation, when unfixedportion 1128 may be within a specified distance and/or angle from flightposition 510, then pressure regulating valve 1440 may open to reduce thepressure in hydraulic line 1422.

Reducing the pressure in hydraulic line 1422 may reduce the output ofmotor 1434. Hence, the force applied to wing fold actuator 1410 frommotor 1434 may be reduced as compared to before pressure regulatingvalve 1440 opens. Hence, forces applied to hold unfixed portion 1128against fixed portion 1126 such that latch 1212 will be aligned as shownin FIG. 12A when lock 1210 moves between engaged position 1232 anddisengaged position 1234.

As a result of the reduced pressure to motor 1434 during engagement anddisengagement of lock 1210 in latch 1212, reliability of and/or meantime to replacement for motor 1434 and/or associated components may beincreased as compared to motor 1434 being powered at a full pressureavailable from aircraft hydraulic power system 1402. As a result of theforce produced by motor 1434 being sufficient to force unfixed portion1218 against fixed portion 1220 so that respective centerlines forunfixed lug 1208, fixed lugs 1204, and lock 1210 are all aligned witheach other, reliability of and/or mean time to replacement for latch1212, lock 1210, lock actuator 1214, and/or associated components may beincreased as compared to a locking system that does not provide a forcesufficient to hold respective centerlines for unfixed lug 1208, fixedlugs 1204, and lock 1210 are all aligned with each other.

The illustrations of FIG. 14A and FIG. 14B are not meant to implyphysical or architectural limitations to the manner in which differentillustrative embodiments may be implemented. Other items in addition to,in place of, or both in addition to and in place of the ones illustratedmay be used. Some components may be unnecessary in some illustrativeembodiments. Also, the items are presented to illustrate some functionalcomponents. One or more of these blocks may be combined or divided intodifferent blocks when implemented in different embodiments.

For example without limitation, hydraulic control module 1406 may becombined into flight controls computer 1414 or into power drive unit1408. Likewise, where as hydraulic pressure system 1400 illustrates wingfold system 1100 as applied to a hydraulic powered configuration,analogous components may be used for a pneumatic powered configuration,or an electric powered configuration. Although FIG. 11 for wing foldsystem 1100 and FIG. 14A and FIG. 14B for hydraulic pressure system 1400only show one type of powered system being used, a wing may have aprimary wing fold system 1100 or components thereof configured with onetype of power supply, and a secondary system, such as without limitationwing fold system 1100 or selected secondary components thereof, with asecond type of power supply.

Thus, a method may exist for controlling an angular free play of anunfixed portion of a wing relative to a fixed portion of the wing whiletransitioning a lock in a latch. Referring now to FIG. 15, FIG. 15 is aflowchart of a method for controlling an angular free play of an unfixedportion of a wing relative to a fixed portion of the wing whiletransitioning a lock in a latch, in accordance with an illustrativeembodiment. Method 1500 for controlling an angular free play of anunfixed portion of a wing relative to a fixed portion of the wing whiletransitioning a lock in a latch may include steps 1502 through 1508.

The method may include regulating a force on an unfixed portion of awing and holding an unfixed lug against a stop device (Operation 1502).The stop device may be connected to the a fixed portion of the wing. Theunfixed lug may be included a part of a latch for the unfixed portion ofthe wing.

The method may include receiving input in a flight controls computerfrom aircraft system sensors and environment sensors (Operation 1504).The input may be received into an algorithm in a processor in the flightcontrols computer.

The method may include regulating a control module regulating a powersupply from a power system to the power drive unit connected to a wingfold actuator (Operation 1506). Regulating the power supply to the powerdrive unit may be via a differential between a first power supplied to afirst line and a second power supplied to a second line, each lineconnecting the control module to the power drive unit. A first powersupplied to the first line by the control module may move the unfixedportion toward a flight position. A second power supplied to the secondline by the control module may move the unfixed portion toward anon-ground position.

The power supply may be at least one of: hydraulic, electric, andpneumatic. When the power supply may be hydraulic, regulating a powerdifferential to the power drive unit may be via a valve in the controlmodule, which may be a hydraulic control module.

The method may include moving the unfixed portion toward the flightposition via moving the wing fold actuator in a direction moving theunfixed portion toward the flight position (Operation 1508).

Further, a method may exist for decreasing a load on a wing foldactuator of a wing, and increasing a mean time between replacement ofthe wing fold actuator, relative to the wing foregoing using theprocess.

Referring now to FIG. 16, FIG. 16 is a flowchart of a method fordecreasing a load on a wing fold actuator of a wing, and increasing amean time between replacement of the wing fold actuator, relative to thewing foregoing using the process, in accordance with an illustrativeembodiment. Method 1600 for decreasing a load on a wing fold actuator ofa wing, and increasing a mean time between replacement of the wing foldactuator, relative to the wing foregoing using the method may includesteps 1602 through 1614.

Method 1600 may begin by receiving status information and environmentcondition information in a processor (Operation 1602). Method 1600 mayinclude executing an algorithm in a program code in the processordetermining a power supply from a power control unit for transitioningan unfixed portion of the wing between a flight position and a foldedposition, based on the status information and environment conditions(Operation 1604).

Method 1600 may include regulating the power supply from the powercontrol unit controlling a force at an output device of a wing foldactuator (Operation 1606). Method 1600 may include activating at leastone of: engagement, and disengagement, of a lock with a latch for thewing (Operation 1608). Method 1600 may include decreasing a load on thelock, thus reducing at least one of: a size and a weight requirement,and a replacement frequency, for a lock actuator, relative to the wingforegoing using the method (Operation 1610).

Method 1600 may further include controlling alignment of a centerlineaxis of fixed lugs and a centerline axis of an unfixed lug with acenterline axis of the lock via contacting the unfixed lug against astop device on a fixed portion of the wing (Operation 1612)

Method 1600 may include engaging the lock with the latch (Operation1614). The lock may include a beveled corner and the unfixed lug mayinclude a beveled opening.

The flowcharts and block diagrams in the different depicted illustrativeembodiments may illustrate the structure, architecture, functionality,and/or operation of some possible implementations of apparatuses andmethods in an illustrative embodiment. In this regard, each block in theflowcharts or block diagrams may represent a module, a segment, afunction, and/or a portion of an operation or step.

In some alternative implementations of an illustrative embodiment, thefunction or functions noted in the blocks may occur out of the ordernoted in the figures. For example, in some cases, two blocks shown insuccession may be executed substantially concurrently, or the blocks maysometimes be performed in the reverse order, depending upon thefunctionality involved. Also, other blocks may be added in addition tothe illustrated blocks in a flowchart or block diagram.

The description of the different illustrative embodiments has beenpresented for purposes of illustration and description, and may be notintended to be exhaustive or limited to the embodiments in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different illustrativeembodiments may provide different features as compared to otherillustrative embodiments. The embodiment or embodiments selected arechosen and described in order to best explain the principles of theembodiments, the practical application, and to enable others of ordinaryskill in the art to understand the disclosure for various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed is:
 1. A method of controlling an angular free play ofan unfixed portion of a wing relative to a fixed portion of the wingwhile transitioning a lock in a latch, the method comprising: regulatinga force on the unfixed portion and holding an unfixed lug against a stopdevice, the unfixed portion comprising the unfixed lug.
 2. The method ofclaim 1, further comprising the latch comprising the unfixed lug.
 3. Themethod of claim 1, further comprising holding the unfixed lug againstthe stop device via a control module regulating a power supply to apower drive unit connected to a wing fold actuator.
 4. The method ofclaim 3, further comprising regulating the power supply to the powerdrive unit via a differential between a first power supplied to a firstline and a second power supplied to a second line, each line connectingthe control module to the power drive unit.
 5. The method of claim 4,further comprising the first power supplied to the first line moving theunfixed portion toward a flight position, and the second power suppliedto the second line moving the unfixed portion toward an on-groundposition.
 6. The method of claim 1, wherein holding further comprises apower drive unit applying a force moving a wing fold actuator in adirection moving the unfixed portion toward a flight position.
 7. Themethod of claim 6, further comprising the force moving a wing foldactuator in the direction moving the unfixed portion toward the flightposition being less than approximately one-seventh of a maximum forceavailable for rotating the wing fold actuator in an opposite directionrotating the unfixed portion toward an on-ground position.
 8. The methodof claim 6, further comprising the force rotating a wing fold actuatorbeing regulated by an algorithm in a processor in a flight controlscomputer, the algorithm receiving input from aircraft system sensors andenvironment sensors.
 9. The method of claim 1, such that regulating aforce on the unfixed portion further comprises a power drive unitcomprising a variable displacement motor.
 10. The method of claim 3,further comprising the power supply being at least one of: electric, andpneumatic.
 11. The method of claim 3, further comprising the powersupply being hydraulic, and regulating a power differential to the powerdrive unit via a valve in a hydraulic control module.
 12. A systemconfigured to limit a force at a wing fold actuator output, the systemcomprising: a power drive unit connected to the wing fold actuator; acontrol module connected to and configured to control power to: thepower drive unit, and a lock actuator configured to lock a latchconfigured to secure an unfixed portion of a wing to a fixed portion ofthe wing; an aircraft system sensor; an environment sensor; and a flightcontrols computer.
 13. The system of claim 12, further comprising theflight control computer comprising a processor comprising an algorithmconfigured to regulate the power drive unit.
 14. The system of claim 13,further comprising the algorithm configured to regulate the power driveunit based upon inputs from aircraft sensors.
 15. The system of claim14, further comprising the algorithm configured to limit, a force thatmoves the wing fold actuator in a direction that moves the unfixedportion toward a flight position, to approximately one-seventh of amaximum force available for moving the wing fold actuator in an oppositedirection and moving the unfixed portion toward an on-ground position.16. The system of claim 12, further comprising the latch comprising afixed lug and an unfixed lug, each lug configured such that a centerlineaxis of the fixed lug substantially aligns with a centerline axis of theunfixed lug and a centerline axis of the lock such that the lock maytransition between an engaged position and a disengaged position suchthat no more than 6,000 pounds force is needed to insert lock throughthe fixed lug and the unfixed lug and into the engaged position.
 17. Thesystem of claim 16, further comprising the unfixed lug configured tocontact a stop device located on the fixed portion via a force from thewing fold actuator moving the unfixed portion toward a flight position.18. The system of claim 16, further comprising unfixed lug configuredcomprising a beveled corner on an opening through the lug such that theforce from the wing fold actuator moving the unfixed portion toward aflight position may be overcome by a force in an opposite direction ofthe force from the wing fold actuator, applied against the unfixedportion by a corner of the lock via the lock actuator moving the lock,such that the lock may move through the latch and into the engagedposition, the corner of the lock being beveled.
 19. A method ofdecreasing a load on a wing fold actuator, and increasing a mean timebetween replacement of the wing fold actuator in a wing, relative to thewing foregoing using the method, the method comprising executing aprogram code in a processor: receiving status information andenvironment condition information; executing an algorithm in the programcode determining a power supply from a power control unit fortransitioning an unfixed portion of the a wing between a flight positionand an on-ground position, based on the status information andenvironment conditions; regulating the power supply from the powercontrol unit controlling a force at an output device of a wing foldactuator; and activating at least one of: engagement, and disengagement,of a lock with a latch for a folding wing.
 20. The method of claim 19,further comprising decreasing a load on the lock, thus reducing at leastone of: a size and weight requirement, and a replacement frequency, fora lock actuator, relative to the wing fold actuator foregoing using theprocess, via: controlling alignment of a centerline axis of fixed lugsand a centerline axis of an unfixed lug with a centerline axis of thelock via contacting the unfixed lug against a stop device on a fixedportion of the wing; and engaging the lock with the latch, the lockcomprising a beveled corner and the unfixed lug comprising a beveledopening.